If an oil's flow rate meets or performs "like" a 20w oil and when elevated to the proper test temp, meets or performs "like" an SAE 50 that particular is a multi-viscosity oil period.

It does not make any difference if the oil was blended with straight cut base stocks or with a polymer.

If thereis a "w" in the descriptor of the viscosity, I am sorry to say, it is a multi viscosity.

Knot 4 me sorry for jumping in your S***, but just because Mercury says something doesn't mean it is correct, espically with something they don't even manufacture.

Ken

No problem. Good info and I stand corrected.

The difference is if an additive was put into the oil to make it a multi-weight. Most synthetics naturally flow better at cold temps but also perform well under high temp/load because they are synthetic.

That's the key differentiator in my mind. :)

Here's an informative article here for the others concerned about using a multi-visc. vs. straight weight; http://www.blackstone-labs.com/oil-viscosity.php

20W50 Mobil ONE

My favorite brand that seems to work best is........FRESH OIL.

Everbody gets their panties in a bunch over what brand is better than the next, 25w40 vs straight 40, and so on.

you can have brad penn, amsoil, royal purple, or whatever you spend 10 bucks a quart on, and if you dont change it often, its as good as junk once it get contaminated with fuel, carbon, moisture, etc.

My advice is use a good name brand 20w50 and use a wix filter, change it often, and keep tune up in top running order. The engines will live a long time. Your 4.3 will be fine with some castrol or pennzoil from wally world.

Big rig engines go a million plus miles, mostly using fleet oils. Diesels or not, bearings are bearings, lubrication is lubrication. Key is maintance intervals.

Teague would likely run dinosaur piss in the race boat if his sponsor requested :drink:

20W50 Brad Penn :eek: there is no other :party-smiley-004:

+1, with the cavet for flat tappets of choosing one with 1000 ppm zinc / phosphorus (good choices in all brands for that).

All the other claims are snake oil. A good brand name oil changed at regular intervals is the key.

yup. Kendall 20w50 titanium is what im using. Zinc is important for those flat tappets.