What kind of oil 94 Sport Nautique 5.8 PCM Pro Boss

[dba4life]

I don't have the manuals here and need to get the oil. What should I use?

Thanks in advance.

[surroundsound64]

Not sure what the manual says, but I'd go with mobile 1 synthetic 10w-30 and a mobile 1 synth. filter.

[Mikeski]

PCM manual says: "PCM does not see any advantage using synthetic lubricants"

Use the dino oil...

I use Chevron Delo 15w-40, of course I also work for Chevron so I am biased.

Others use Shell Rotella in the same weight with good results. It's basically diesel oil.

[cabcadd]

My manual recommends 15w-40.

[dba4life]

Thanks guys. I saw 15w-40 mentioned a lot when I searched the forum but I just wanted to make sure for the Pro Boss.

Kevin

[Mikeski]

I didn't realize until now that you were talking about a Ford...

PCM recommends straight 40w in the Fords. I ran straight 40 in my GT-40 but I also let warm up for at least 15 minutes since I have a 15 minute ride through a 5mph zone from my dock. If I didn't always warm it up I would have used the 15w-40 so it would get adequate oil when cold.

[dba4life]

Hello,

I got the Shell Rotella T Heavy Duty SAE 15w-40 oil at Walmart tonight. Then I saw this post. So I dug the manual out of storage (We are moving). It recommends SAE 40 oil. Says you can use 20w-40 or 20w-50 if it meets the API classification of "SG".

I am looking at the bottle of Rotella and I do not see "SG" rating. It is rated for CI-4Plus, CI-4, CH-4, CG-4, CF-4, CF/SJ, SL

I am assuming I should go back and find SAE40 oil? I also dug up the last time the oil was changed at the dealer and they used SAE40.

94 Sport Nautique with the PCM 5.8 Pro Boss motor.

Thanks
Kevin

[darrel409]

I run Valvoline straight 40 wt in my pro boss, changed every 50 hrs. 600 hours no leaks or problems to date. I keep double track of hours by documenting in my log book (kept in my manual) and i write the date and hours on the filter with a sharpie. Its a good system for me.

[slob02]

YES..........40W

[davidr]

The Shell 15W40 should be just fine. SJ, SL exceed the SG rating.

What's magical about straight 40 weight?

Makes more sense to me to run 15W40 than a straight 40 weight. Better high temperature protection, better low temperature flow/lubrication and less risk of blowing seals on a cold engine.

Above 100C, a straight 40 weight actually has lower viscosity than a 15W40 oil, and all engine oils are excessively viscous below operating temperatures anyway (worse with a straight weight than a multi-vis).

For example:

an exemplary Castrol straight 40 weight,
40 C - viscosity 129.9
100 C - viscosity 13.8

an exemplary Castrol 15W40,
40 C - viscosity 112
100 C - vicosity 14.7

(see e.g. http://www.castrol.com/castrol/datasheetsearch.do for exemplary data sheets...)

The only theory I know of for advocating straight 40 weight on a performance basis is one I've heard in an airplane context, and the possible advantage is only when the engine is off - the straight weight's greater viscosity when cold implies it might stick better to engine parts, and thereby might provide better corrosion protection in engines that are not used for long periods of time.

I don't think straight 40 weight is bad. I just think a 15W40 oil is better.

[surroundsound64]

All that being said, I believe I'd go with the 15W40.