[JFP in PA]

Originally Posted by shadrach74

Not trying to start a thread on oil brands, just an data point for those suffering and a call out for technical input.

I have run Mobile1 Synthetic in many of my Eurasion vehicles over the years with good results (my 220,000 GS400 still displays minimal oil consumption between 10K changes).

I am too swamped for a DIY at the moment, so I had my local shop change my oil recently. They filled my 2002 S (81,000) with Motul synthetic 5W-40 instead of M1 synthetic 0W-40 I've used at home.

When I picked up the car, there was zero rattle on start-up. Engine was cold, so I assumed someone had recently moved the car outside and that the tensioners were still full of oil. The next morning when I started the engine The lack of noise got my attention. There was a barely audible difference in mechanical noise for the first .10th of a second, but not really what could be considered a rattle. The car is no longer "embarrassing" to cold start up in front of people.

Can any one explain why heavier weight oil would pressurize the tensioners faster than lighter weight oil...especially on sub freezing mornings?

I'm baffled by this.

Higher base weight oils typically demonstrate higher film strength than their lower base weight analogs. This increase in film strength results in slower drain down over time and that gives better parts coating at start up. What you are seeing is the most commonly observed result.