In the related post, Rage poste quote,

Mobil 1 15W50 is API rated SN/SL Is it ok because they say SL or not ok because they also say SN?

Mobil 1 20W50 V Twin is API rated SH, SG/CF, CD. SL is not mentioned.

Mobil 1 4T 10W40 Motorcycle racing oil is API rated SM, SJ, SH/CF, JASO MA. SL is not mentioned.


Never got a real response before it turned into and oil filter debate. I have been running M1 15w50 with no problems so far but haven't been inside to see what it looks like. Getting ready for an oil change and was going to run 15w50 again but what is the latest news???

Without a doubt they have reduced zddp. I was a Mobil 1 15W-50 fan for years, but I switched to the Mobile 1 V-twin oil which seems to be a slam dunk. My advice is that if you want to use synthetic, stick with the known best, Mobile 1 Vtwin, Amsoil Dominator Racing Oil or Royal Purple. I like to always have a reason to spend more. I think there is enough evidence to abandon the 15-50 and go with others.

I recommend reading the Related FAQ's at the bottom of this link. Does a very nice job of summarizing the current ZDDP level issue in motor oil.

If you are running a fairly mild roller cam motor I don't think you should have any concern running Mobil 1 15W50 with its current levels of ZDDP. If you've already purchased some and have concerns running it, just add some Cam Shield or equivalent to raise the level of ZDDP.

Is this anything to be concerned about in a stock 496HO?

I was curiuos about this, as the website still has the 1200 PPM showing. So, using htier webpage, I asked if the concentration of zinc had been lowered in the M 1 15W-50. Here is the response I got about an hour ago:

Unfortunately, my local wallyworld doesn't carry 15W-50 now, but it is obviously still good for flat tappets, as everything I've read says 1200 ppm is the level that used to be in oil.

That is good to know that the level is still 1200ppm. I will continue to use it if I can find it cheap someplace. This season going RP.

I like the Valvoline Not Legal oil as well. Will look into getting that. Would be great for older engines.

I contacted Modil and they also stated that the level is still at 1200 ppm which is fine since you need at least 1000 ppm to sustain life with a flat tapet cam but then I asked the question of what the percentage or ppm of the detergent additive package was whick offsets or dilutes the "z" package and I got silence. Come to find out it is in the neighborhood of 3800 ppm and that take the original below the safe level. I was not happy with the attitude of the customer service either and that goes a long way with me. I spoke with Joe Gibbs today and got real answers and also one of my best friends is the head engine builder at Nortech and that is all they run is the Joe Gibbs HR 15W50 so that is what I am going with.