Engine oil for LPG

[thatfatbloke]

I was just about to order 6 litres of 5W30 for the LS,when I suddenly wondered if I should be using a different viscosity for an LPG engine. Googled it of course,but it made things worse!. Any thoughts most welcome. Ta.

[dendonc]

1 minute ago, thatfatbloke said:

I was just about to order 6 litres of 5W30 for the LS,when I suddenly wondered if I should be using a different viscosity for an LPG engine. Googled it of course,but it made things worse!. Any thoughts most welcome. Ta.

No, 5/30 is what I use (ASDA), mine was converted by Profess S Wales in June 2013.

[Beejay55]

Having run LPG cars for 15+ years I can confirm that there is no need to buy something other than the manufacturer-recommended viscosity.  You will notice that you are able to increase the period between changing the oil.  

[rz1c13]

Interesting topic. I would like to hear arguments supporting using 5/30. However what I hear from experienced mechanics - some working for the dealers, the x/30, be it 0/30  or 5/30 are very thin / low viscosity oils. They tend to burn off, combust, get consumed, whatever.... much more easily than x/40 or x/50 due to lower resistance to high combustion temperatures. The good (and probably the only one) side of x/30 is that due to low visc. there is less resistance to moving parts of the engine and lower fuel consumption, you may get a bit more power, or you may think you will... and we are more "eco-friendly…". As the eco-histeria gets pushed further, the dealers of course will recommend 0/30 or 5/30. However, because the oil film of x/30 is much thinner, you get more engine wear - and this is what our lovely car dealers want: you scrap your car at around 150-200k miles and go and get a new one. I have lived it myself, used to get 5/40 full-synthetic from asda for my mazda 323f 2.0, Wasn't too bad, but once I tried Mobil 1 5w50 (not recommended by the dealer by the way), the car stopped consuming oil, engine and valves got much quieter and I have no soot deposit on the chrome end of the tailpipe anymore! So what is this eco-histeria about... By the way I did not notice an increase in fuel consumption.

Now onto the LPG. The combustion temperature of LPG-air mixture is higher than petrol (I'm guessing 20-30%), moreover, if an LPG installation is fitted/tuned by an amateur, or someone who doesn't know your engine inside-out, you'll soon get the valves burnt out, and plus if running too lean, in some extreme cases holes burnt through the piston... (yes, I've seen it too). So I see no reason why anyone would get a thin, low viscosity oil for an LPG engine - quite the opposite if you think from the point of the running conditions of the engine. Get at least 0w40, or even 5/50 fully synth.

I'm currently on 0w/40 Mobil 1 (full-synth) on my LS430, and the car is LPG powered and happy. I want to test Mobil 1 5/50, the same as on the mazda at some point, and I don't think it would hurt the LS V8.

 

 

 

 

[sorcerer]

I've had LPG cars for the last 10 years and only ever put in whatever oil the manufacturer recommends (viscosity-wise, not necessarily brand-wise) and I've had no problems whatsoever.

LPG runs cleaner than petrol so on intervals of about 9k miles between changes, the oil usually comes out almost as clean as it went in; not quite, but almost.

Quote

if an LPG installation is fitted/tuned by an amateur, or someone who doesn't know your engine inside-out, you'll soon get the valves burnt out,

Almost all Jap engines and a lot of others besides will, or could, suffer from this so you fit a Flashlube kit to prevent it. Some people may say you don't need to but it's much better to err on the side of caution and spend a few quid on the Flashlube, rather than hundreds putting preventable damage right.

[rz1c13]

Yes, totally agree. The LPG oil looks pristine at around 10k miles. Just got the LS, but also have a 1994 Nissan primera at 330k on the clock, LPG on it for over 15 years, running on fully synth Mobil 1 5w/50.

[rz1c13]

14 minutes ago, sorcerer said:

Almost all Jap engines and a lot of others besides will, or could, suffer from this so you fit a Flashlube kit to prevent it. Some people may say you don't need to but it's much better to err on the side of caution and spend a few quid on the Flashlube, rather than hundreds putting preventable damage right.

Depends, and not necessarily, For example the new Prins installations for engines with direct injections of liquid phase gas don't need that, in fact the LPG in liquid phase helps to cool off the valves. My personal feeling is that the old Jap engines, like on my primera P10, 1994 were made much robust and designed with a high margin tolerances for temperatures and such. I've been running this Nissan for over 15yrs on LPG with no valve lube, and compression testing it - no change whatsoever.

[Bluesman]

Just the normal recommended oil for mine. Redressing the drip feed oil to stop the valves burning. Once they did away with leaded petrol  to run your engine on unleaded you  needed to put Redex or some similar oil additive to help stop the valves burning out or you could take the head or heads off and have the valve seats hardened and that was also needed for LPG but modern engines are capable of running  on LPG without any drip feed oil additive which they love to charge £100+, a complete waste of money. I have never heard of any valves being burning out because of LPG. The other thing to remember is that LPG has only 85% of the calorific value of the same amount of petrol.

[rz1c13]

1 hour ago, Bluesman said:

I have never heard of any valves being burning out because of LPG. The other thing to remember is that LPG has only 85% of the calorific value of the same amount of petrol.

Yes if the installation is done right, on the right engine there should be no concern. However, on some poor quality engines they (valves) happen to burn, even running solely on petrol !!! - some new 4.0L grand cherokees love it - so forget an LPG on that, or find out for yourselves. My neighbour just killed one cherokee like that. Another example is  when an LPG installation is not fine-tuned and running the engine too lean - for many reasons - carelessness, clogged gas filters, worn gas injectors, or because the customer wanted to skimp on LPG fuel consumption and/or the shop wanted to brag the customer that they will fit an LPG and the MPG will be as good as on petrol...

Yes, so to compensate for the lower caloric value, a typical LPG will consume about 10-20% more fuel, but again, a decent LPG has easily an octane value above 100, so if the fuel maps of the engine are tuned well, or if the software of the engine can learn and adjust to this octane dynamically, the results can be astonishing, especially power-wise. Most of the LPG is composed of butane and propane. Butane has higher caloric value, and burns hotter, but not so good in freezing conditions, propane is the one less caloric, but burns better when cold (much lower  freezing temp) - that's why the LPG for  winter has (or should have) different proportions propane/butane than LPG for summer - on some engines in extreme temperatures you can feel the summer/winter difference.

Now about LPG quality. I'm from Poland, do a lot of driving back and forth from the UK, and sadly must say that LPG quality (and the power your car can get from it) is not consistent across the countries, and even filling stations. In relative terms, Polish gas is ranges from poor to average, sadly, BP in Poland IMHO is not impressive at all. Belgium and Netherlands have consistent quality, but not impressive, UK the same. What stands out is Germany, and only specific stations: I can trust any ARAL - I have tried many of them, and all of them have 100+ octane petrol too. Last trip I filled on a German Total, pricey, 72 cents/litre of LPG, but my nearly 25yr old primera 1.6, 16v on carburettor (!) started flying. Engine got so responsive and eager like never. 190 km/h top speed on that LPG, while usually struggled to top 160-170. Note - it's got a lightly advanced timing to account for higher octane petrol or LPG. Just before Dunkirk I stopped on Belgian Texaco to re-fuel, 42 cents/litre, and... so disappointed - acceleration was like driving through wet cement.

Just converted an LS430, and testing, so the time will tell, but so far I'm very happy - running last BRC Sequent Plug&Drive conversion kit. I did the conversion in a Lexus approved garage, with 2yrs warranty etc. I was also surprised to hear that now in Poland many dealers (if you request) will outsource an LPG conversion and sell you a brand new LPG powered car, and this will not affect warranty, your rights, etc.

 

 

[sorcerer]

I'm not sure I agree about the differences in LPG quality Robert.

Every car I've had on LPG has been a 3.0 V6, the last one being  a Nissan Maxima QX and my current one being my Lexus RX300, and I think I've done about 200,000 LPG miles in total between them. The vast majority of miles covered have been here in the UK but for the last twenty-odd years we've been driving around Europe for our holidays.

We've driven from Preston, Lancashire to the far reaches of Poland (spending time in the Tri-City of Gdansk, Sopot and Gdynia, Torun, Szczecin, Poznan, Krakow, Zakopane, Bialystok and Lublin amongst lots of other places), Czech Republic, Slovakia, Hungary, Latvia and Lithuania, as well as Germany, Belgium and France, and I can honestly and truthfully say that we've never noticed any difference in performance whatsoever, no matter where we have filled up. Of course, these journeys have always been during the summer and with a fully-loaded car - maybe winter temperatures and different loads would make a difference, I don't know.

The Nissan had an OMVL Dream XXIn and the Lexus has a KME Nevo Pro (or may be a Nevo Plus, I can't remember - and as it's after midnight I'm not going out to look ) and both systems have always run as smooth as silk, with no differences between LPG brands/places or between LPG/petrol.

[rz1c13]

Thanks for sharing your experience John.

I think there are significant technical differences here, and therefore our experience is different, no doubt.

Your engines are fairly big compared to my 1.6 primera - not the main point but it has to be sad that if you have a 200 - 300 horsepower at your disposal, you won't really notice let's say 10  or 20 missing because of low fuel quality, to be precise because of low octane and/or caloric value. It's a different story on an old or better put very simple engine running on a carburettor with fixed ignition timing (i.e. my primera), compared to a more modern engine where the ECU software is quite flexible and can re-map the fuel/air proportions, fuel dosage  and ignition timing dynamically in order to give you consistent and good ride without sacrificing performance. What you will notice though, is that if you fill with low octane petrol or low quality of LPG, the fuel consumption will go up. I've heard some mechanics saying that you have to burn a tank or two of good high octane petrol for the engine to re-learn and adjust - not sure how much practical truth is in that, but sounds plausible.

Most cars are typical daily rides, and will accept a wide variety of octane value, but these cars are rather tuned towards the lower numbers (around 90 and higher). You can still put 100+ in them but you may not notice that much improvement, maybe a few % better mpg, and a smoother running engine. Tuning for low end of octane is simply a safety margin, i.e. if you happen to drive through Ukraine, or Poland and fill up on a shady station you won't blow your engine. But if you decide to take things in your own hands and re-map the ECU for higher octane petrol 98 or 100+ or a better LPG, you will definitely enjoy sharper acceleration and better mpg, there's no doubt about that, especially if your engine is turbo-charged. The problem I see here, however, is too much risk. Especially for LPG, as there are no standards of octane or "quality" of LPG as there are for petrol. Believe me or not, there is excellent, average and, awful LPG out there.

I think that my old primera is a good testing platform for fuel. The engine has got at  all times one stiff base setting for fuel/air proportions, does not try to compensate, re-learn for one or another octane number, and has one fixed ignition timing that you can set yourself on the ignition distributor - which is currently lightly over-advanced. This is why I can better feel the quality of fuel, as it is the only one parameter that changes in the whole experiment. In modern engines there are so many parameters adjusted dynamically + quality of fuel comes into play, so I agree you may have trouble figuring out the cause from the effect or any difference at all.

On the quality of fuels my impression is that outside Germany everywhere else is worse, especially for LPG, and the more to the east or south you go it gets worse and inconsistent. In Poland alone, throughout say last 10 years there were  a few nation-wide petrol related scandals uncovered. Stations selling 98-100 octane on the label and after lab tests turned out it hardly had 95. The 95 labelled one had barely 90, and so on. And much worse things like unusually high water amount in fuel, etc. LPG contaminated by shreds of metal particles and scum. Many people got engines damaged and tried to claim that from the petrol stations. And in some cases that was not necessarily the stations creating the scam, it was also corrupt one level above, the fuel was already like that when arrived from our national refinery, that's why I've said nationwide scandals.

One last note - I have no personal reasons to praise Germany, or complain about Poland, just telling the reality from my perspective. **** sometimes happens no matter the country, but where big money and politics/govt/regulators mix. Look no further than the last VW emissions scandal...

 

 

 

 

[sorcerer]

Interesting points Robert and thanks for the detailed explanation. I can indeed see the logic in your reasoning and I agree that your 1.6 Primera will show up things that my car wouldn't.

Cheers my friend

[dendonc]

18 hours ago, sorcerer said:

We've driven from Preston, Lancashire to the far reaches of Poland (spending time in the Tri-City of Gdansk, Sopot and Gdynia, Torun, Szczecin, Poznan, Krakow, Zakopane, Bialystok and Lublin amongst lots of other places), Czech Republic, Slovakia, Hungary, Latvia and Lithuania, as well as Germany, Belgium and France,

Sounds like you had the good sense to give Chorley a miss

[sorcerer]

20 minutes ago, dendonc said:

Sounds like you had the good sense to give Chorley a miss

We always give Chorley a miss Denis 

[dendonc]

17 minutes ago, sorcerer said:

We always give Chorley a miss Denis 

Yea, although I'm sure David Attenborough would be in his 'discovery mode' element there.

[tfh_md1]

On 9/1/2017 at 6:47 PM, rz1c13 said:

Interesting topic. I would like to hear arguments supporting using 5/30. However what I hear from experienced mechanics - some working for the dealers, the x/30, be it 0/30  or 5/30 are very thin / low viscosity oils. They tend to burn off, combust, get consumed, whatever.... much more easily than x/40 or x/50 due to lower resistance to high combustion temperatures. The good (and probably the only one) side of x/30 is that due to low visc. there is less resistance to moving parts of the engine and lower fuel consumption, you may get a bit more power, or you may think you will... and we are more "eco-friendly…". As the eco-histeria gets pushed further, the dealers of course will recommend 0/30 or 5/30. However, because the oil film of x/30 is much thinner, you get more engine wear - and this is what our lovely car dealers want: you scrap your car at around 150-200k miles and go and get a new one. I have lived it myself, used to get 5/40 full-synthetic from asda for my mazda 323f 2.0, Wasn't too bad, but once I tried Mobil 1 5w50 (not recommended by the dealer by the way), the car stopped consuming oil, engine and valves got much quieter and I have no soot deposit on the chrome end of the tailpipe anymore! So what is this eco-histeria about... By the way I did not notice an increase in fuel consumption.

Now onto the LPG. The combustion temperature of LPG-air mixture is higher than petrol (I'm guessing 20-30%), moreover, if an LPG installation is fitted/tuned by an amateur, or someone who doesn't know your engine inside-out, you'll soon get the valves burnt out, and plus if running too lean, in some extreme cases holes burnt through the piston... (yes, I've seen it too). So I see no reason why anyone would get a thin, low viscosity oil for an LPG engine - quite the opposite if you think from the point of the running conditions of the engine. Get at least 0w40, or even 5/50 fully synth.

I'm currently on 0w/40 Mobil 1 (full-synth) on my LS430, and the car is LPG powered and happy. I want to test Mobil 1 5/50, the same as on the mazda at some point, and I don't think it would hurt the LS V8.

 

 

 

 

Hi Robert - I've just converted a Citroen C5 X7 (150K miles) to LPG (sorry Lexus owners for invading your forum) and it is supposed to take a 0W30 (ACEA C1) engine oil. I was wondering whether using a 0W40 or even a 5W50 would be preferable. Clearly a bit more fuel consumption but would the wear of parts be significantly reduced. BRC supplier says just to use the same oil as in a petrol engine, but I seem to burn more oil when running on gas. I'll probably test the Ow/40 Mobil 1 but I am tempted by the 5W50 Mobil 1 too.