> OTOH you hear people saying that if the oil has a notice on the can saying
> it fills the various specs why pour more money into the sump than
> you need,
> just use the generic oils sold by the big discounters.
API specifications are created by oil makers and car manufacturers, each
with their own agenda. None of those agendas include your getting the
maximum life out of your vehicle. In fact, they tend to be the bare minimum
required to get your drivetrain to last beyond it's warranty period (and IMO
increasing warranty periods are the fundamental reason the specifications
have been increased so many times).
Without exception, manufacturers of engines with very long warranty periods
(eg Mack, Cummins, and my employer John Deere) have their own specifications
for oil ... which very few of the oils found in 'discount' stores meet. Of
course, that's somewhat appropriate since most long-life engines are diesels
(which have somewhat different requirements for oil), but even the API specs
for diesel engine oils just aren't good enough for a 300,000 mile engine.
And even then, they don't particularly care about getting more power out of
a drivetrain.
There was an article in one of the US 'muscle car' magazines a few years
ago, where they ran a car on the chassis dyno using conventional lubricants,
then changed all the lubes to synthetic and did another run. They found 7%
more horsepower at the rear wheels. Given my yearly budget for lubricants,
I have no problem with paying twice as much for that much more power.
Since nothing else changed in their test, that 7% had to come from reduced
friction and increased efficiency ... meaning it should also increase gas
mileage and reduce wear, giving an extra bonus. Might even help with that
overheating problem !
And of course I can't prove that the engine in my Chevy (rated one of the 10
worst cars in the US by Consumer Reports) wouldn't have gone 250,000 miles
if I hadn't used high quality lubricants ... but I sure think it played a
part.
Ok, that's what I think ... YMMV of course
Randall
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