WALTSTAR

76FJ55

Just keep an eye on your oil pressure. You should be fine.

FredR

What is the question?

hacker-pschorr

Tell your friend not to drain the sump until they have the proper amount of the oil they think they should be using.

WALTSTAR

V2Rocket

youll be fine, just don't beat the thing too hard if ambient temps are 100+.

FredR

Calculating the resultant viscosity of mixing two oil streams is somewhat complex and without going back to my process engineering books I cannot give you a number off the top of my head but obviously the resultant will be somewhere between the two indices.The difference in viscosity will not cause any short term issues. Perhaps more of concern is the effect of mixing two different lube oils. There is a small risk that the additive package used in one oil may not be compatible with the additives of the other oil when the two are mixed. If the two oils used were from the same manufacturer that risk would probably be minimal to non existent as they would invariably use similar additive packages..

Speedtoys

Youll be fine.

Maybe fix it right soon, and for sure have parts before the job next time.

But, y0u cant find this anywhere else???

928 DesMoines

I had this issue once...... and went to a different store. But, while I have always been oil true to my P-cars. I have ***** nilly oil comboed in my 1997 sentra for years. 248k on that baby going strong.

PaulD_944S2

Not too difficult to calculate effective viscosity if we assume:
1. Oil change for Porsche 928S4.
2. Oil change will be 8 quarts.
3. Same brand and type of oil.
4. One container is full of 5 quarts of 20W-50 oil.
5. One container is full of 5 quarts of 10W-40 oil.

Therefore let:
5 qts 20W-50 oil = _5 x 20W = 100, ____5 x 50 = 250
3 qts 10W-40 oil = 3 x 10W = + 30, __3 x 40 = + 120__________________________130____________370 (these are arbitrary units)

Divide each sum by 8 (total number of quarts)
For vvW side 130 / 8 = 16.25
For vv side 370 / 8 = 46.25

So, based on simple math. the net effective viscosity of the oil = 16.25W-46.25, or rounded to a viscosity of 16W-46 for 5 quarts of 20W-50 and 3 quarts of 10W-40 in the sump. If the engine used 1 quart of oil and was refilled with 20W-50, then the net viscosity would move from 16W-46 towards 20W-50. And remember, there were assumptions made to determine the net effective viscosity. Ain't math fun.........

Real world results may yield close but somewhat less predictable results, however the concept remains.
See:
https://bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=47655
https://www.superstreetbike.com/engi...busters#page-3

Moral: always have two oil changes of oil on hand. This was much harder to type up than it was to calculate!

WALTSTAR