Engine oil.

[prh77]

   Here is a quick question for everyone; what type and viscosity oil do you use? My '88 Universal 25XP manual specifies straight 30, but I am wondering if the 15-40 Rottella might be the way to go.

[Ken Heyman]

I've always been a believer in OEM specs and consequently use 30 weight oil. Are you having a problem? Why would you want to change the reccomended viscosity?

Ken

[prh77]

No problems, I just figure my manual was written 21 years ago, and oil formulation has changed. I also think about those spring and fall engine starts here in the Northeast when the temps are around 45F.

[Stu Jackson]

I just did a search on "engine oil" and found this:  http://c34.org/bbs/index.php/topic,4793.0.html

Among many others.  Give a search a try   , there is a lot of interesting information, some contradictory, some supportive.

Our engines haven't changed, and the only oil changes have been the additives and the C sub-letter on the oil jugs, all discussed in the link above and others found in the search.

[Jeff Kaplan]

peyton, up here in the northeast i stick with chevron delo300, which is straight 30w. as was discussed in length, you can use shell rotella 15w-40, industry standard in the trucking industry. if you live in a climate where you can leave your boat in longer than my 5 month season, a multi vic oil can be used. here with our short season, a straight 30w gives the engine all the protection needed. your choice...jeff

[Ron Hill]

I used 10W40 Mobile 1 synthic in my old engine for 20+ years. 
I'm using 15W40 as a break in oil for my new engine and at layup this fall will switch to the closest Mobile 1 synthic to 15X 40 as I can get.
It's a good idea to always use the same brand oil as the additives could clash.  A thought

[Mike Vaccaro]

Multi-vis provides a bit of flexability if you sail year round, but you can't go wrong with straight 30 weight.  Ron's point is valid about mixing/changing brands.  The most important thing to remember is to change your oil frequently--25-50 hour intervals maximum, depending on your operating temperature (lower oil temps mean more frequent changes).  Although most of us don't have oil temperature gauges, the important thing is to ensure that the oil is allowed to heat to at least 180 degrees F each time the engine is run.  If not, any water present from condensation will not boil out of solution, and will eventually combine with other contaminates that are the buy products of combustion to form acid. 

Along with a supply of clean fuel, frequent oil changes are the most inexpensive preventative maintenance you can do for your small diesel.

[Roc]

I've been using straight 30 weight since new.

[Braxton]

I use CHEVRON DELO 400 LE.   My understanding is its basically the Chevron equivalent of Rottella but my local Napa outlets carry it while for some reason the don't consistently have Rotella.

The link posted by Stu seems to have the definitive discussion.   I only went with the Delo after reading it far to many times.