# anyone running on lpg



## shreksnr (Sep 17, 2011)

Hi anyone running on lpg and what mpg do you get compared to petrol. Colin


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## bigcats30 (Aug 13, 2012)

LPG MPG is the same as Petrol...infact I lie its actually lower because it doesn't produce the same amount of energy so uses more....its only cheaper and less pollutant

and you still have to run petrol now and then otherwise it will kill your engine (LPG doesn't lubricate like petrol)

And don't let anyone tell you different as its rubbish.


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## rowley (May 14, 2005)

I ran a car and motorcaravan on lpg some 10 years ago. MPG was approx 20% less on lpg.


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## Zebedee (Oct 3, 2007)

bigcats30 said:


> and you still have to run petrol now and then otherwise it will kill your engine (LPG doesn't lubricate like petrol)
> And don't let anyone tell you different as its rubbish.


I had never thought of petrol as a lubricant Bigcats?

Can you explain how it works please.

Dave


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## bigcats30 (Aug 13, 2012)

Zebedee said:


> bigcats30 said:
> 
> 
> > and you still have to run petrol now and then otherwise it will kill your engine (LPG doesn't lubricate like petrol)
> ...


Petrol, Diesel, Kero etc etc all come from oil.....they all lubricate...its why LPG conversions have to have petrol run through them now and then as the moving parts need lubricating (fuel pump etc).


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## Enock (Nov 11, 2011)

Not a motorhome but this is my LPG experience

4.7 V8 Grand Cherokee...now on 130,000 miles... LPG fitted at 50k...

So 80,000 miles on LPG...car does around 17mpg on LPG.... When I had, an injector problem in the early days, and had to run on petrol for a couple of weeks, it did around 20, 21 MPG...

As for having to run on petrol.... It depends on the engine, I NEVER run petrol, as my Jeep starts on Gas...in the same way as our fork lifts at work... They never had petrol tanks, and did thousands of hours on LPG with no additional lubricants..


My previous jeep Cherokee 4.0 was on 225,000 when sold... Was converted at 90k...


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## bigcats30 (Aug 13, 2012)

Enock said:


> Not a motorhome but this is my LPG experience
> 
> 4.7 V8 Grand Cherokee...now on 130,000 miles... LPG fitted at 50k...
> 
> ...


LPG is a dry burning fuel....you will ruin an engine by not lubricating it.....they can add lubricant at service intervals

Rubbing metal together with no lubricate = failure

Not only that the seals in an engine need lubricating....(normal engines do that from the oil and fuel) again LPG engines need lubricating just like any other engine (even electric motors need lubrication)


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## motomike (Aug 27, 2012)

When I was at work we ran a large fleet of cars and vans on LPG. Many had problems with fuelling, high tickover, spluttering, etc..
I used petrol whenever I could. 
On LPG expect at least 10% less to the gallon.

The set up ensured cold starts were always on petrol, and when warmed up would (or should) switch to LPG.

My experience has tainted my view of conversions...but somebody must like it.

MM


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## Enock (Nov 11, 2011)

bigcats30 said:


> Enock said:
> 
> 
> > Not a motorhome but this is my LPG experience
> ...


It depends on the engine whether it needs any additional lubrication... Jeeps are well known for not needing it...my experience backs that up
Others are well known for needing it

This is the view of a well respected LPG forum on the use of FLASH LUBE. An additional lube that is injected into the cylinder head

"It all depends on how hard the valve seats are and that depends on the grade of steel used by the manufacturer. If it is a Land Rover, BMW, Mercedes, Saab, Vauxhall, Jaguar and one or two others, you don't need it. If it is Japanese, or other far Eastern, you almost certainly do need it. Others vary on the engine, Ford's Zetec 4 cylinder engine has a reputation for having valve seats made of butter and will wear valve seats running on unleaded petrol with it's additives for example (planned obsolescence?) whereas other Ford engines are much better. It all depends on the engine."


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## Bill_H (Feb 18, 2011)

bigcats30 said:


> Zebedee said:
> 
> 
> > bigcats30 said:
> ...


Errrr
LPG also comes from oil
Liquid Petrolium Gas


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## bigcats30 (Aug 13, 2012)

Bill_H said:


> bigcats30 said:
> 
> 
> > Zebedee said:
> ...


Errrr

But it doesn't lubricate.....


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## Zebedee (Oct 3, 2007)

bigcats30 said:


> Bill_H said:
> 
> 
> > Errrr
> ...


Why not?

Now I'm really intrigued - though I confess that organic chemistry was not one of my best subjects. :roll:

Dave


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## bigcats30 (Aug 13, 2012)

Zebedee said:


> bigcats30 said:
> 
> 
> > Bill_H said:
> ...


Ok.....it does lubricate....but not nearly enough to prevent damage to metal moving parts.


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## listerdiesel (Aug 3, 2012)

Oh dear!

Lots of pitfalls by the sounds of it!

LPG has been around for years and years, fork trucks in food warehouses use it as the exhaust is not toxic. I can remember fitting LPG kits to fork trucks at W C Youngman Ltd in Crawley in the early to mid 1960's.

Since we all went green and took out Tetra-Ethyl Lead, there hasn't been a lot in petrol that lubricates, but it does have the cooling effect from vapourisation of the fuel that LPG does not. LPG runs through a vapouriser to ensure that only vapour is fed to the engine, so is actually fairly warm when it goes into the engine.

We run a 1999 (built November 1998) Discovery 2 V8 which has petrol or LPG as a fuel. We have twin sill tanks and retain the full petrol tank capacity.

We regularly tow heavy trailers, including our 3.5tonne trailer/RV which we take our Ruston-Hornsby engine to shows in.

There is a small loss of power on LPG, I'd have said that a good multi-point injectioned engine probably loses less than 5%, but carburetted engines are not as good as the fuel distribution is uneven.

We have just completed 50,000 miles in three years on petrol and gas. We start on petrol, but this time of year it is on gas within a mile or so.

We have had no issues with the gas side, other than a tank solenoid valve that went open circuit fairly early on. We have changed the gas valve seats and filters as required. The original installation was done in 2005 by a guy in Ashford, Kent. He has uploaded new software to the gas ECU for me so we are up to date.

Valve seat life is as good as on petrol. We fitted a new short engine to the car in July 2009 (we bought it on ebay with a duff engine) and the original heads were re-used. We ground the valves in at the time and recently had a water leak when we replaced the head gaskets as precaution, and the valves just needed lapping in again. That was 4000 miles ago.

Now: If you want to convert, the engine MUST be in good mechanical order with all aspects such as cooling system etc fully 100%. It is preferable that you have multi-point injection as this method allows the gas to work in the same way.

Most gas systems that are multi-point will use the petrol ECU, MAF, temperature and Lambda sensors for working out the fuel mixture, but instead of the ECU driving the petrol injectors, it switches to working the gas injectors instead.

Here's a picture of the gas valves on top of the inlet manifold:










Switching backwards and forwards is pretty simple, it is automatic going from petrol to gas, and much the same going the other way. You get a slight jolt at the changeover, but most of the time you don't notice it.

Oil quality has a bearing on engine life, and with LPG it does have a major cooling function. We run 10W-40 DIESEL semi-synthetic oil in the Discovery, never a sign of any lubrication problems and the engine is sparkling inside. this picture is at 46000 miles:










Note that some deposits remain inside the rocker compartment from its previous life.

MPG is comparable with petrol, we get 10mpg on gas towing the big trailer in hilly country, but that improced to 16mpg in Holland which is flat. Daily running around solo we get about 14-18mpg, maybe a bit more if we don't go on motorways.

We would say it has been good for us with no reservations, despite a lot of horror stories about engines exploding etc etc., especially on the Discovery V8 engines. In practice I have no qualms in recommending a conversion, with the caveat that you must go to a guy that knows what he is doing (there is a trade association for converters) and the vehicle must be in good mechanical condition as far as the engine goes.

*Benefits: *

Oil stays cleaner, longer. After 8000 miles, the oil is still transparent on the dipstick, we change at 8000 miles rather than 6000 as there is no contamination of the oil from combustion products.

Engine stays cleaner internally, less deposits in the engine:










Here is the head at the time of the rebuild, valves cleaned and lapped in, but seats not reground:










Cheaper to run.

We run Champion Double-Platinum spark plugs, LPG is slightly hotter than petrol and the gap needs to be slightly wider than for petrol.

*Drawbacks:*

LPG availability in the UK is not as good as it should be, but you soon learn towork out a list of filling points, and there are various directories available on a yearly basis.

Holland uses the same filler coupling as the UK, and LPG is almost at every filling station, especially motorways.

Cost: £2100.00 approx for a V8 Discovery, less for 6 and 4 cylinder cars.

It can enhance the value of the vehicle when fitted, so that has to be taken into account.

*Conclusion:*

For us, it has worked well. We have no issues with it at all, and if we changed car we would have another one like a shot with the same system.

Sorry for the long post.

Peter


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## Enock (Nov 11, 2011)

listerdiesel said:


> *Conclusion:*
> 
> For us, it has worked well. We have no issues with it at all, and if we changed car we would have another one like a shot with the same system.
> 
> ...


Your experience pretty much mirrors mine....
I too use a 10/40 oil and it stays spotless between changes, which I've extended from every 6k to every 10k miles

Mine is an OMVL MULTI point sequential system... And Appart from an injector issue, after first installation, I've had 80,000 trouble free miles...
The Jeep uses no oil or water, and the engine runs perfectly...

My friend has the same Jeep allbeit the HO (high output) version... He's on 175k, and still going strong..

Like you, when replacement time comes, I'll be following a similar path


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## Zebedee (Oct 3, 2007)

listerdiesel said:


> Since we all went green and took out Tetra-Ethyl Lead, there hasn't been a lot in petrol that lubricates . . .
> Peter


Ah yes - I thought it was the lead that gave most of the lubrication, but I didn't want to be a smartarse and get shot down in flames! :roll: :lol:

I remember having to put in an additive when unleaded petrol was first introduced, for fear of burning the valve seats!

Halcyon days - when anybody with a bit of mechanical skill could fix most things on a car. Now you need a computer and an IT degree! :roll:

Dave


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## teemyob (Nov 22, 2005)

*Thread*

I am watching this thread with great interest.

We gave a 70,000 mile Toyota Previa to our Daughter and Son-In-Law.

They love the car, Twin A/C, Twin Sunroofs, ABS, Fridge, 7 Seats, Vast Boot, the monty.

But the the Fuel Economy is poor.

I looked at loaning them the £1,000 or so for a conversion but do not want to kill the engine. I have heard good an bad reports about LPG conversions. Including a good one first hand from another Previa owner that turned bad.

The Engine is in great condition, as is the rest of the car. Was one of the very last Original mid engine Previas registered in the UK (W, 2000).

But they only travel around 6,000 miles a year.

TM


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## shreksnr (Sep 17, 2011)

*lpg/ mpg*

Thanks guys very helpful info, seems I need to get my system checked out,, anyone know a good lpg garage in SE London/ Kent area. Colin


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## listerdiesel (Aug 3, 2012)

*Re: lpg/ mpg*



shreksnr said:


> Thanks guys very helpful info, seems I need to get my system checked out,, anyone know a good lpg garage in SE London/ Kent area. Colin


Talk to Peter Feacey at EnergyShift in Ashford.

http://www.energyshift.co.uk/Home.html

Very honest guy who has provided us with excellent service and backup.

Peter


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## rowley (May 14, 2005)

TM, at 6000 miles per year I would not consider converting to lpg.


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## Enock (Nov 11, 2011)

rowley said:


> TM, at 6000 miles per year I would not consider converting to lpg.


Same here..... You'll never get. Payback.... Just not worth it IMO


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## ched999uk (Jan 31, 2011)

Please do not increase oil change intervals. It's not just the 'deposits' in the oil that determine it's life. Oils get 'chopped' up inside an engine and this reduces their sheer strength (ability to withstand pressure). Also any non FULLY synthetic oil burns of the light elements of the oil. These light components are the additives. It's the additives that gives oil it's abilities.
A full synthetic oil has all the additives chemically bonded to the base oil so when oil is burnt off you just burn off a volume of the oil not just the additive pack. 

I am simplifying things above but please do not just increase the oil service interval because the oil looks 'clean'. There is much more to oil than how clean it looks!


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## listerdiesel (Aug 3, 2012)

ched999uk said:


> I am simplifying things above but please do not just increase the oil service interval because the oil looks 'clean'. There is much more to oil than how clean it looks!


The manufacturer's oil change requirements for my 1998/99 3.9 litre Discovery is 6000 mile periods, the oil change for our 2007 2.5 litre Renault Trafic diesel is 12000 mile periods. The oil is the same in both cases, the Discovery is a petrol V8 with Bosch multi-point engine management, the Renault is a turbo diesel.

What makes the service period of the diesel Renault longer than the petrol Discovery on the same (diesel) engine oil?

Basically the oil is better now than it was 14 years ago when the Discovery was built and the oil specified in the handbook.

I'm very comfortable with a 30% increase in oil change service periods, to date there have been no issues at all with the extended periods, and the only other thing that is affected is the oil filter, which is basically changed with the oil.

We run long-life plugs with a service life of 80000 miles as well.

The following selected items are taken from Wiki:

"The technical advantages of synthetic motor oils include:
*
Measurably better low- and high-temperature viscosity performance at service temperature extremes

Decreased evaporative loss

Extended drain intervals with the environmental benefit of less oil waste.

Improved fuel economy in certain engine configurations.

Longer engine life

Increased horsepower and torque due to less initial drag on engine"
*

http://en.wikipedia.org/wiki/Synthetic_oil

Peter


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## ched999uk (Jan 31, 2011)

listerdiesel: I am not trying to start an argument just trying to impart some of my experience of oil testing for MoD.
In your post (with nice images) you said that you were using 'semi synthetic' oil. The wiki details are about synthetic not semi synthetic oils. A semi synthetic can be a 'normal' mineral oil with a small % of synthetic added. So not it does not have the properties of a full synthetic. The 'semi' is just a marketing gimmick to charge more for oil. You are better off looking for a fully synthetic with an API spec that meets or exceeds the manufacturers requirements. 

You are quite correct that oils have improved over the years as have engine developments. 

One thing that you may not be aware of is that the detergents within oils has actually decreased over the years due to manufacturers worrying about the damage that they do to catalytic converters!

Overall it's your engine and you obviously know how to look after it from your photos. The 'same diesel' oil will probably have a API spec for petrols as well (API/SG?). 

My worry is that others read about extending oil changes and think it's OK to extend them without any other knowledge.

I would not dream of telling people what to do, I hope my post did not come across that way.


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## shreksnr (Sep 17, 2011)

*lpg/ mpg*

Had Peter from Energyshift check out my lpg system , made a couple of adjustments and some good advice a real gent . Hope to improve my mpg . Colin


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## listerdiesel (Aug 3, 2012)

*Re: lpg/ mpg*



shreksnr said:


> Had Peter from Energyshift check out my lpg system , made a couple of adjustments and some good advice a real gent . Hope to improve my mpg . Colin


He is a nice guy, very helpful and good to deal with.

Peter


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## listerdiesel (Aug 3, 2012)

ched999uk said:


> I would not dream of telling people what to do, I hope my post did not come across that way.


Not at all, I didn't take it that way, just quoting my own experiences and the general view within the LPG community.

Peter


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## blongs (Jan 12, 2009)

I have a converted Astra Sporthatch and the petrol 44mpg drops to the 35mpg predicted by the online calculators and the advice given at the time. 

Generally you get 80% of the economy of what you were getting on petrol.

I converted at 50,000 miles/3 years old when i moved house. The payback was calculated at 30,000 miles of lpg running I think. 

Now at 122,000 miles and 6 years old.

We were out and about over the bank holiday and managed to get some lpg at 63.9 p/l (72.9 at my local) so the pence per mile on the fuel dropped into 8p a mile. Normally it works out to 9p a mile. 

Petrol at @ £1.329 p/l and 44mpg would be about 14p a mile.

(Motorhome Diesel @ 1.399 and 25mpg about 24p/25p a mile)

Ben


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## j20ands10 (Sep 16, 2010)

I have read this with interest as I to am considering converting my MH to lpg, estimated yearly savings are £500+ which takes into account the 20% drop in MPG and is based on true MPG and true fuel costs only guess was the historic lpg price.

The reason I am looking at it is I was toying with a conversion to gaslow but just can not warrant the outlay for a 10yr return. which got me thinking could a LPG conversion for the engine run both the engine and habitation? local installer shut today but going to call him monday also surprised no one has mentioned this as lpg conversion for habitation always seems to be a hot topic, which makes me think it might not be possible or a bad idea.

A 3yr return for would seem more practical, plus the gains associated with a gaslow install.


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## john56 (Oct 14, 2012)

Until i retired i was a fleet manager for a fork truck company, we had about 120 trucks on hire maybe 50 were gas trucks, none ever run on petrol and some had done upto 10,000 hours, all they needed was regular servicing and i never saw an engine that had worn through wear due to the use of LPG, i had also converted a Rover V8 landrover to LPG, that never ran on petrol and would start on gas with no need for choke, 3 yrs of ownership and 30,000 miles and it still ran sweet as a nut.
The only problem could be after prolonged use would be valve seat wear due to the lack of lead lubricant thats found in petrol on older engines ( pre unleaded petrol).


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## listerdiesel (Aug 3, 2012)

j20ands10 said:


> I have read this with interest as I to am considering converting my MH to lpg, estimated yearly savings are £500+ which takes into account the 20% drop in MPG and is based on true MPG and true fuel costs only guess was the historic lpg price.
> 
> The reason I am looking at it is I was toying with a conversion to gaslow but just can not warrant the outlay for a 10yr return. which got me thinking could a LPG conversion for the engine run both the engine and habitation? local installer shut today but going to call him monday also surprised no one has mentioned this as lpg conversion for habitation always seems to be a hot topic, which makes me think it might not be possible or a bad idea.
> 
> A 3yr return for would seem more practical, plus the gains associated with a gaslow install.


We bought the Discovery for its towing capacity, and being a V8 4.0litre with LPG already fitted it was a good choice.

When we built the trailer last year, we decided to go for Autogas in the trailer as well, and fitted a Tinley Tech vapour tank with twin fillers, one each side as the trailer is 6.3 metres long.

Can't speak for Gaslow, but our own setup has worked well for us. We have water heater, cooker hob/grill, oven and fridge on gas.

Peter


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