summer oil 20w50 Castol GTX HM for the fun of it

[Russell]

My summer/warm weather oil will be 20w50 Castol GTX High Mileage blend with Mahle filter just for the fun of it. My car seems to like heavier oils as it run quieter. :)

[south26]

Ya I run 20w50 in the summer in my 535i e34. The m30 likes the heavier oils and in the winter I run 10w40. That is what the owners manual recommends for it also.

[Russell]

I do wonder if 20w50 works ok with vanos on the m50 engine. Seems I ran heavier weight several years ago and it was fine.

[Russell]

well. it seemed to have lifter tapping noise this morning for a couple of minutes. The temps we below 60 and car had a 12 hour soak.

[genphreak]

I understand 20W50 to be the recommended weight for M50B25.

Changes on weather/location I know (but I don't get why- the engines run at the same temp no matter what the weather is, the temp is controlled by the radiator thermostat/fan- down to a point. If below 10 degrees outside, the engine must run below half- if that happens, I can see one needing to run a lower weight oil.

Any members out there have a needle sit below half? Anyone know if my theory is correct?

My preference these days is Penrite 10W60 synthetic- M30, M50 and M60. I'd prefer 10W50 and don't very much like Mobil/Esso/Shell/Caltex/Gulf/Castrol/Texaco/BP/Enron stuff.

[93 525 Paul]

Having disassembled and updated the vanos unit in my E34M50TU I can tell you the high mileage original had very little wall tension between the teflon outer o-ring and the vanos bore cylinder wall. The viton o-ring beneath the teflon outer ring was rock hard and provided almost no wall tension.
Based on that I'd GUESS the hi mileage vanos engine would like a higher viscosity (thicker) oil to minimize blow by.
Just a guess.

[Russell]

Having disassembled and updated the vanos unit in my E34M50TU I can tell you the high mileage original had very little wall tension between the teflon outer o-ring and the vanos bore cylinder wall. The viton o-ring beneath the teflon outer ring was rock hard and provided almost no wall tension.
Based on that I'd GUESS the hi mileage vanos engine would like a higher viscosity (thicker) oil to minimize blow by.
Just a guess.
Thank you. I like your observation about the vanos.

[bennyg]

Cant speak re bmw (only use penrite or other good full synth 10w30/10w40)

but 1.5L of 20w50 valvoline mineral crap topping up the mazda (1.8L 4 pot which has only ever had 10w30 full synth and except for soft manifold screws -which decided to let go 30 hours before our son was born - has never had any other problem in 150k/10 years) did seriously bad things to the piston rings and other seals.

Moral of story, dont mix!