I was curious to know who has tried running a xw-20 in a car that specified 5w-30. I read a UOA of someone who did it their miata and a civic. If an engine does not exhibit symptoms of blowby, compression loss, and oil consumption, then how much of a bad idea would it be for someone to consider using the lighter weight oil? Would changing to a lighter oil viscosity increase the chances of such symptoms as listed above? I wonder if these new xw-20 oils being as shear stable as they appear from UOA's have adequate film strength comparable to their xw-30 counterpart? I expect most cars sold in the United States within the next ten years to specify these 20wt oils. Someday there may be a 0w-10, who knows.
[ March 08, 2004, 06:52 AM: Message edited by: HondaRD ]