Originally Posted by minxguy
(Post 2821122)
Rage, the viscosity gets to low because of the elevated temps, hence the pressure will drop. Remember all oils thin with heat.
With the thinner viscosity (due to high heat or fuel dilution) the oil film can't support the load of the application. With thinner viscosity oils tighter bearing tolerences and higher pressures will solve the problem of "falling" thru the fluid flim. Ken |
One has to wonder what the oil pressure was in a 1986 Mercruiser engine with 1986 oils at 300F+ oil temperature.
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Originally Posted by Rage
(Post 2821191)
One has to wonder what the oil pressure was in a 1986 Mercruiser engine with 1986 oils at 300F+ oil temperature.
If you ran at those temps, a multi-vis 20w50 would THIN LESS, therefore be more viscous (thicker) than a straight 50. The same would apply to 40vs10w 40 or and multi-grade vs the straight weight version of the 210 side. It has nothing to do with the "year" of the lubricant. Viscosity is viscosity, be it 1986 or 2009. Ken |
Originally Posted by minxguy
(Post 2821204)
Depends on the viscosity of the engine oil.
If you ran at those temps, a multi-vis 20w50 would THIN LESS, therefore be more viscous (thicker) than a straight 50. The same would apply to 40vs10w 40 or and multi-grade vs the straight weight version of the 210 side. It has nothing to do with the "year" of the lubricant. Viscosity is viscosity, be it 1986 or 2009. Ken |
Not sure if this is the right place to ask this, but, what oil does would be the best to run in the Mercury Racing 525. Also drive lube. I'm running Bravo X drives behind the 525's, so I want something that will help with the extra HP. I plan to change engine oil and drive lube every 25 hours. (That was the advice from the guy that installed the engines for me.
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Originally Posted by Rage
(Post 2820936)
Attached is supposedly a Mercruiser Service Bulletin from 1986 on acceptable oil temperatures in Mercruiser engines. Anyone know the history of this bulletin?
I posted it on another site. |
If Mercury endorses 280F oil temperature as OK in their engines what is the resulting oil pressure that by default is also OK in Mercruiser engines running at 280F oil temperature?
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Originally Posted by Rage
(Post 2821860)
I thought I read on this thread that over the years the oil grade rating systems have become more and more performance stringent resulting in better and better performance out of the oils. That is what I ment thinking that this meant that an S_ grade in 1986 was not as good an oil as an SL is today. Is that incorrect?
Your oil in 1986 had more anti wear than the current oils of today. Ken |
Originally Posted by Rage
(Post 2822027)
If Mercury endorses 280F oil temperature as OK in their engines what is the resulting oil pressure that by default is also OK in Mercruiser engines running at 280F oil temperature?
Oil viscosity, bearing clearance, different oil pump, etc. Ken |
Originally Posted by redbud35
(Post 2821899)
Not sure if this is the right place to ask this, but, what oil does would be the best to run in the Mercury Racing 525. Also drive lube. I'm running Bravo X drives behind the 525's, so I want something that will help with the extra HP. I plan to change engine oil and drive lube every 25 hours. (That was the advice from the guy that installed the engines for me.
I change every 20-25 hours. Ken |
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