I've been running conventional Castrol 20W-50 in my 380sl all summer because it significantly reduced the smoke I was getting while accelerating on exit ramps after highway driving, probably due to worn rings or valve stem seals.

But now that the temperatures are starting to go down, I wanted to have a lower oil viscosity at start up, and still have the higher viscosity when the car was hot. So, after seeing a number of good reviews, I was thinking about trying Castrol 5W-50 Synthetic, assuming that it doesn't start or exacerbate the leaks that some people have experienced in their older engines.

I was therefore wondering if anyone has used this oil and, if so, how it performed.

Thanks in advance for any info anyone can give me on this.

I use mobil 1 15w50 syn in my M116....I see M1 has come out with a 5w50 also.

I'd imagine it would perform similarly to what you have now, as the 50 weight is what matters when the engine is at operating temp to prevent the issue you mentioned.

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