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Racing Oil in Crusader 6.0L Engine

R

Russf

Member
I am told that Mobil 1 Racing oil has more of something called ZDDP which significantly reduces friction v. regular synthetic oil. This should only be used in racing or boat engines because it will diminish the effectiveness of catalytic converters. Appreciate your thoughts.
 
I tend to think positively of high zinc oils. I ran an Amsoil equivalent called "classic engine" or similar. You can also add ZDDP to oil separately.
 
I would say you don't need the high levels of zinc in the 6.0.....most of the valve train is 'rollered' ...... the manual should tell you which SAE grade is appropriate (adequate).....
 
Thanks guys. My inclination is to go the Mobil One 15W-50 for a boat kept in the Seattle area. That oil has high levels of zinc and potassium which greatly reduce friction. The manual recommends 15W-40 which Mobil One does not sell. Any thoughts?
 
Diver. Is your advice based on the fact that the heavier oil will cause the engine to run hotter? My 6.0l Crusaders run at about 180f when run at 3500 RPMs. I seldom run them at more than that. I am not sure what weigh the prior owner used which is still in the engine just that his comprehensive service log says Mobil One racing oil.
 
Just did some more research. Mobil One 15w-50 is considered racing oil so I suppose that that is what is in the engine now.
 
You want the THINNEST oil consistent with enough oil pressure when the engine is at its hottest. So, both after a hard, long run at cruise; is both the idle and cruise oil pressure correct.
Why Thin? To help FLOW during warm up. PRESSURE cold is fairly immaterial.
As the shell bearings wear, it might be necessary to increase viscosity of the oil, to maintain hot pressure.
I'm not sure the intent with racing oil. Are you racing this boat? Are you rebuilding the engine frequently, like racers?? Are you running 300 deg oil temperature?
 
As I said in my first thread the prior owner used racing oil which I believe was Mobil on 15W-50. The boat is not raced. It is a Tiara 2900 with two 6.oL Crusader engines. The manual says the 20W-40 should be used and synthetic is OK. The engines run at about 178-180 F when cruising at about 3500 RPM. I have delved deeply into this because that is the way I am with things on my boat. I am going to call Mobil tomorrow and get its advice. Will keep the thread posted.

Thanks again to all.
 
I'm trying to give an engineering based view on how Crusader recommends oil grade. Crusader wants a 40 oil in their engines, and has for many years. In the "old" days, straight 40 was recommended, and multi-viz oil was specifically NOT recommended. Why? Hard running, high shear marine engines broke down multi-viz mineral based oils. in the last 20 years, some major things happened to change Crusaders' philosophy. Roller cams, low shear oil pumps, and synthetic oils. THere is no good reason now to try to force a straight weight 40 oil into bearings at start up. So, now we can enjoy a 40weight oil that keeps our pressure while HOT, and a oil that makes its way into small clearances cold. As good as we have available, anyway. bottom line; wide spread oil, synthetic, 40.
Worst choice: 20w-50 mineral, next worst: straight 40, best may be 0w-40, but it has to be synthetic to not have viscosity modifier breakdown.
 
"Racing oil" is not very useful in determining content...and
potassium won't help much with the friction.....

The mobil-1 15W-50 will do just fine if you want to pay for it...and a roller valve train modern engine doesn't need 'elevated' zinc or phosphorus so there's little benefit to paying for them....

The best approach is to use regular oil analyses and a brand name oil consistent with the OEM guidance....
 
Boat engines work hard whenever it is in gear. It is like climbing a mountan pass pulling a trailer full of rocks as soon as you let off the gas the boat stops. That is why progressive timing advance is so important. Just as important is oil changes with a OEM equivalent grade of oil. You can greatly increase engine life by not running max WOT rpms that is used for proper prop pitch. Run the engine/s around 3/4 throttle or max spark advance, and if you have an appointment just leave earlier and enjoy the ride.
 
I called the Mobil One number and asked for advice on the following.

1.Engine manual recommends 15W-40 which is only available in synthetic for Diesel. Used in Puget Sound where the ambient temp. i usually over 50 degrees F.

2. I said that I believed that Mobil One 15W-50 was used by the prior owner.

3. I asked would Mobil One 15w-50 be acceptable.

4. The man who answered did not seem to know as much as I did about engine oil. It took several tries to get him to understand that I cannot use the recommended oil-15W-40-because Mobil One does not make that in a synthetic.

5. Instead of advising me as to the suitability of 15W-50 from a technical standpoint he merely said that If it worked for the prior owner it should work for me. I noted that short of an engine teardown I could not know if it was working. Bottom line he said impliedly that I should just defer to the judgement of the prior owner. Amazing.
 
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