Recommended oil for 350i
Discussion
I use Mobil1 15W50, and have no problems. I change it every year, so about 2k - 3k miles. Fram PH2821A filter.
Agree about the thin stuff - its correct for a new Jap engine with tolerances like a gnats chuff, but its no good for the rover engines - clearances too loose and you wont get either the flow or the pressure because it'll all leak back past the pump gears!
Agree about the thin stuff - its correct for a new Jap engine with tolerances like a gnats chuff, but its no good for the rover engines - clearances too loose and you wont get either the flow or the pressure because it'll all leak back past the pump gears!
Used 15/40 in the past without problems. Changed every 3000miles.
Changed to 20/50 after some fettling and oil pressure improved, even a bit high when cold. Will stick with 20/50 from now on. As mentioned before, oil filter changes are as important. Tip: if filter is changed quickly during oil change, no issues with priming of the oil pump. If you leave it too long (like going out to buy a filter) be careful as no oil pressure will wreck your engine.
Rob
Changed to 20/50 after some fettling and oil pressure improved, even a bit high when cold. Will stick with 20/50 from now on. As mentioned before, oil filter changes are as important. Tip: if filter is changed quickly during oil change, no issues with priming of the oil pump. If you leave it too long (like going out to buy a filter) be careful as no oil pressure will wreck your engine.
Rob
And just to add (perhaps sucking eggs):
The high number is the hot running rating and 50 indicates the oil stays thick (as in not too thin) when hot. Lower numbers give less thick or in our case too thin oil. It seems I got away with 40, but the thermostat and my standard 350i engine has very stable 84-85 degrees when hot and not on a track. If stable >90 degrees, 40 probably would be too thin.
The low rating is the thickness at low (equals engine starting) temperatures. the lower the better in theory, as lower means thinner and easier to start the engine with good flow and thus good cold start protection. Remark: Most important as wear is caused mainly during cold starts.
Summary: Seems that the RV8 is designed for hot temperature 50 rating. And the larger the difference for cold to hot the more difficult/compromised the oil is and thus 15/50 is about the maximum in variance between handling cold/hot conditions and 20/50 is a good compromise.
If XX/60 has been advised to you, it is definately too thick at normal hot running temperatures and the flow the engined is designed for (not pressure) is negatively effected.
Then you have mineral, semi-sythetic and synthetic. Synthetic is the best(even here are variations and types....) and longer intervals & higher output engines benefit from this - engine life between overhauls is maximised. Semi-synthetic is ok for standard engines and not hard worked engines. Mineral could be ok, but low mileages oil changes are then required.
Bit of a rambling, but my excuse is that I like my wedge and are an automotive engineer by the way.
Other questions ask opieoil here on pistonheads...
What to use in your gearbox is a totally different matter (just teasing).
Rob
The high number is the hot running rating and 50 indicates the oil stays thick (as in not too thin) when hot. Lower numbers give less thick or in our case too thin oil. It seems I got away with 40, but the thermostat and my standard 350i engine has very stable 84-85 degrees when hot and not on a track. If stable >90 degrees, 40 probably would be too thin.
The low rating is the thickness at low (equals engine starting) temperatures. the lower the better in theory, as lower means thinner and easier to start the engine with good flow and thus good cold start protection. Remark: Most important as wear is caused mainly during cold starts.
Summary: Seems that the RV8 is designed for hot temperature 50 rating. And the larger the difference for cold to hot the more difficult/compromised the oil is and thus 15/50 is about the maximum in variance between handling cold/hot conditions and 20/50 is a good compromise.
If XX/60 has been advised to you, it is definately too thick at normal hot running temperatures and the flow the engined is designed for (not pressure) is negatively effected.
Then you have mineral, semi-sythetic and synthetic. Synthetic is the best(even here are variations and types....) and longer intervals & higher output engines benefit from this - engine life between overhauls is maximised. Semi-synthetic is ok for standard engines and not hard worked engines. Mineral could be ok, but low mileages oil changes are then required.
Bit of a rambling, but my excuse is that I like my wedge and are an automotive engineer by the way.
Other questions ask opieoil here on pistonheads...
What to use in your gearbox is a totally different matter (just teasing).
Rob
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