Originally Posted By: tig1
I ment in 1960. Dino oil caused all kinds of sludge then. Many old timers will testify to that.
Old habits die hard and frankly, those were the days where (up until the late 80s/early 90s where most motor oil was at borderline Gp1) motor oil, even if they passed API specifications, cannot be guaranteed as far as oil oxidation resistance, cleanliness, etc. concerned.
Moving forward to ILSAC GF specifications: if you to look at the soon-to-be-coming-to-your-neighbourhood GF-5 specifications, it requires motor oil to not only pass all the industry's standards as far as valvetrain wear, etc. but also oxidation resistance and self-cleanliness, etc. that only modern Gp2+ or blend with other Gp base oil can achieve. GF-4 is also based on this idea but with slightly older requirements that came along during the late 90s/early 00s.
Call it anyway you want but I simply cannot see the correlation RE: motor oil serviced some 40yrs ago has to do with modern API SM/ILSAC GF-4 (or soon to be coming GF-5) as far as sludge prone and oxidation-resistance's concern.
Again, I just can't stressed enuf that lubricant technologies have come a long way during the past 20yrs, so much so that even the lowly OTC conventional oil sold these days are far superior to that back in the late 80s, letting alone those from yesteryears (60s).
Just take your pick and drive happy.
Q.