hvac, to answer your question simply, I’d say Pennzoil and Chevron Supreme. Both Group II+ base oils and very potent-looking additive packages. Also, we have excellent used oil analysis (UOA) results from each ... rivaling and even exceeding results from some synthetics. Of course, this assumes you have no interest in pursuing a specialty oil like Schaeffer.
I don’t know how many brands and engine combos people know of on this site, but there aren’t many and there are a lot of other variables including driving style, route variations, climatic variations, etc … which come into play.
Lab testing of used oil samples is the only way to know for sure when you’ve found an engine & oil combo which works really well.
As for the high-mileage oils, most have an ester component for some seal swelling. Usually, this merely counteracts some oil’s tendency to leach plasticizer out of seals making them brittle and prone to leaking. Early Mobil 1 (PAO) formulations had this problem but it was corrected a decade ago.
There’s also some debate as to how effective these high-mileage oils are at
stopping leaks so at best, their effects are very mild. When it comes to leaks, the best way to fix them is seal replacement. Expensive, though, especially if they have to pull the motor. Don't expect a bottled product to produce miracles. Maybe stop a slow weeping or slow down a slightly faster drip. That's all.
I’d go with the Pennzoil High Mileage Vehicle out of all of these.
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Bror Jace
