por917

I have been using Mobil 1 20/50 in my 1981 928 for 23 years. I have been hearing lately that Mobil has changed it's composition and that it is now not a good idea to use it in the older cars. Has anyone got any input about this and facts to show this true or false. I would like to continue to use Mobil 1 in my car and hate the idea of changing now. I have 103000 miles on it now. Thx for any input.

SeanR

If you've been using it for 23 years, no reason to change it.

A lot of us are using 15w 50 M1 due to some report that the ZDDP is better.

mickster

15W50 @ Wallymart is cheap in 5 Liter bottles :-)

James Bailey

His point is well taken, when the "IT" changes and Mobile One used to be synthetic but after they lost a big lawsuit it is petroleum based and more recently the additive package changed as well. The heavy duty truck oil Mobile One as used and extensively tested by Doug Hillary is probably a good substitute.

Daniel Dudley

Brad Penn, Valvoline VR1, Royal Purple, Red Line, Amsoil.

Take your pick. 20/50 M1 high performance is OK. Extended Performance is not

beentherebaby

Mobil and others change their formulations without notice so this is always a challenge. The zinc (from ZDDP) level can be determined from a virgin oil sample for comparison of the new and old formulations. Many oil companies recently lowered ZDDP in most of their oils but some changed additive packages to compensate for reduce zinc.

drwhosc

all motor oil has changed. fed law requires lower levels of zinc and phosphorous. went to a pca meeting last month, and this was discussed in depth. Our cars need the older zinc and phosphorous levels because of the alloys used in the moving parts. Turns out there is no real good way to add this stuff back once it is taken out. So the racing oils mentioned previously do overcome this issue. Go to wally mart, advanced auto, etc, and yo may find more metal bits in the sump pan.

dprantl

Or you may not. Do a search. Mobil 1 15W-50 that you can get at Wal-Mart still has 1300PPM zinc and 1200PPM phosphorus which is good for the 928 engine.

Dan
'91 928GT S/C 475hp/460lb.ft

Rob Edwards

Or use whatever you want and toss in a bottle of this:

Mark SF

"when the "IT" changes and Mobile One used to be synthetic but after they lost a big lawsuit it is petroleum based"

I tried my best to understand this sentence but could not.

Mark SF

Yes, here's the table :

http://www.mobiloil.com/USA-English/...duct_Guide.pdf

Bill Ball

15/50 still has good zinc and phoshporous levels, as mentioned and shown in the table Mark linked. The oils that have lower levels are the lower weight "eco" CF-4 oils.

jon928se

Or SM rated - To pass the SM rating requires much less ZDDP. Not all progress is good.

9x8

Strangely enough, 15/50 is rated as SM here:

beentherebaby

FWIW- U.S. / Euro Mobil and many other brand's oil formulations have different chemistry.