I was reading through my factory maintenance manual today and noticed that the oil recommendation for higher ambient temperatures is 15w40 viscosity. That is normally associated with diesel engines. I live in Texas and normally run 5w30. Has anyone run this higher viscosity oil (15w40) in their R53 and, if so, did you experience any problems? Any recognized advantages?

 

I'm no oil expert but, IMHO, 15W40 isn't necessary and a bit too high up the viscosity chart. 0W40 or 5W30 is fine. LubriMoly 5W40 might be a good compromise for you. I'm running PENNGRADE1 15W40 in my 993 Porsches and 289 HiPo engines primarily because of the flat tappet cams and the necessity for higher ZDDP.

 

15W40 seems awfully thick. My owners manual says 5W30 or 5W40 in higher ambient temperatures. I live in Phoenix, AZ and have been running 5W40 for several years.

 

On the surface, I agree with you. I normally run Quaker State 5W30 synthetic. The Bentley recommends 15W40 for higher temps though. I've never used it -- just curious if anyone ever had. Today, I changed the oil ad used Valvoline Restore and Replace 5W30 that is supposed to have superior cleaning properties. It was recommended to me by my son who works for Valvoline. We'll see on the next oil change if it lives up to the hype. My tune provides a nice decel burble which means it's a bit rich and there's unburned fuel in the cylinder that makes the cute noise. That additional unburned fuel creates more soot so my oil gets dark more quickly (as do the edges of my exhaust tips). I change the oil in my MC40 after <3,500 miles which is all I drive in a year anyway.