Oil discussion

[bobcowan]

Originally Posted by joyridin'

On a turbo car, synthetic can make a huge difference due to the coking point being a lot higher. The bearings int he turbo won't fry when you shut down the engine.

As for the Mobil 1 not being true synthetic, he's full of it. It is true synthetic oil just like the Amsoil. He can feel it being faster? LOL...sure.

That's the big advantage of synthetic oils - heat management. A true synthetic can handle a lot more heat for a longer period of time. Sometimes that's an important feature, most times it's not.

M1 is not a true synthetic, unless you're using 20W50 motorcycle oil - about $15 a qt. Standard M1 start with a dino oil, and then is highly refined.

Originally Posted by ERA Chas

Agreed that the evidence of UOAs is the most significant.

You're using the term (..the oil) "lasts" a long time. But is it not possible that the Harley puts fuel contamination in the oil and the diesel does not? That would be true of any brand or type of oil you use-synthetic or not. Did the UOA say something like that for you to use the term "lasts"?

The UOA measures the additive package - among other things. When the additives run out, it's time to change the oil. The additives are used up by things like heat cycles, total heat, fuel and water contamination, etc.

This is the latest UOA for my Cummins turbo diesel. I use Valvoline Premium Blue CJ diesel oil - a straight dino oil:

ROBERT: This oil run lasted a little over 6,000 miles and wear for the most part read around averages.
Copper read a little higher than average, and may show excess wear at a brass/bronze part. While 28 ppm
is above average, copper's wear rate (ppm/mile) is still much better than we saw in the last two samples.
The oil was in good shape physically, containing no fuel or coolant. Insolubles, which are oxidized solids
caused by heat, use, and blow-by, read low at 0.4%, showing good oil filtration. The TBN read strong at 7.0,
lot of active additive left. Try 7,500 miles next.