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.
Engine oil for LPG
in LS 400 / Lexus LS 430 / Lexus LS 460 / Lexus 600h / Lexus 500h Club
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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.