Keith Atlanta

Do you have oil temp t-stats?

07DominatorSS

There should be no need to mix the two. And to whomever stated above, a 20w50 and 15w50 are the same the oil when hot, both 50 weights, so you should see very little difference, more than likely none between the two when at operating temps. We've been selling AMSOIL products for nearly 30yrs, and yes the Zrod will work in the marine application, but personally the Dominator Racing 15w50 is probably the best choice, due to these high performance motors running 5-6k R's constantly! The Dominator has more zinc than the Zrod, which makes it stronger, however, it does not have as strong of an off season rust and corrosion inhibitor package as the Zrod, but should be more than sufficient. Run the Dominator, along with the EAO 24 for your 496ho's, Severe Gear 75w-110 and the Series 2000 Racing Grease on any zerk fittings and you'll be a very happy customer!

SDFever

My manual oil pressure gauge (Snap-On MT37) matches my digital one and now the analog one since i installed the correct sender.

SDFever

yes

SDFever

No one was talking about mixing 20/50 and 15/50. I said in a prior message that i mix 2 qts of straight 60 in with Dominator 15/50.

Also, your oil tech dept that you referred me to was really not very impressive. Please don't take it personally. But it's a real PITA when you take time out of your day to go out and find or buy packaging, drive to ups store and send in stuff and the so-called engineers ignore the feedback.

I've known a lot, I mean a lot of engineers who really were not that smart. The text book only goes so far..

07DominatorSS

I don't disagree with you about the Tech dept, and I kinda forgot about that analysis you sent in. I will follow up with that today!

Now to the mixing, I understand you were mixing straight 60 with the 15w-50, but why? Its not really going to do anything for you. Also, I was referring to the guy that said his pressure was quite different between the 20w50 and the 15w50. It shouldn't be at all. They're both 50 weights at operating temperatures.

Keith Atlanta

At what point does operating 'temperature' come into effect?
Your statement is theoretically correct but, whenever I ran 15W50 it set the low oil pressure alarm off after a hard run - but never did with 20W50. (pre rebuild but even now its lower than I would like) The only simple explanation is the oil since the filters were the same and the conditions were the same.

07DominatorSS

Here are the data sheets on the two products, and yes there is a bit of difference in the viscosity at 100degC, but shouldn't be enough to set an alarm as opposed to the other. What was the pressure reading after a run like that? And believe it or not, it could be the filters. Yes, they may be the same, but sometimes one may be a bit more restrictive than the previous, not likely, but possible. Hey, don't get me wrong, they're all great products and will work great!

http://www.amsoil.com/lit/databulletins/g2883.pdf

http://www.amsoil.com/lit/databulletins/g2570.pdf