Will one of the high mileage 5w-30's have a better chance of holding it's viscosity over a conventional 5w-30? I'm talking over a 3,000-4000 OCI. I know regular Maxlife is part synthetic so I figued the 5w-30 might hold it's viscosity.
Will one of the high mileage 5w-30's have a better chance of holding it's viscosity over a conventional 5w-30?
Yes. Because HM oils are typically blended on the thick side, they will hold their vis better.
Take a look at my recent UOA on Castrol GTX HM 5w30. It was in use 14 months and 4000 miles but was still 11.2 cST, which is a solid 30wt. Most regular 5w30s will drop into the 20wt range over their service life.
The 5-30 and 5-30 HM shear about the same. The HM starts at a higher vis and drops about the same amount of vis as the 5-30 but stays in the 30 range. If you want to stay 30 over your OCI and don't need the sealers, you could just add 1 or 2 qts 10-40 to 5-30 or just use 10-30.