Originally Posted By: cptbarkey
there are a few engines that would not like it, a hemi with mds, and the chain driven subaru's. probably others but in general 5w30 will be fine in yours.
How does this myth continue to perpetuate?
If you understand that viscosity changes massively more with temperature than the difference between the various grades at 100C you know this cannot be true.
In the winter, I was effectively running a much heavier oil in my MDS-equipped Charger than I am right now due to the difference in ambient temperature. The MDS worked properly then and works properly now. No difference in operation.
In my M5, I am running a much heavier oil until my oil is "up to temp". Yet its VCT (VANOS) operates fine. It also operates fine on 10w-60, as the earlier cars with the same VCT system spec'd.
I'm not sure what part about a Subaru having a timing chain makes your point, but I would love to hear it.