Mixing Engine Oil

[Ken Juul]

Jeff,
Alot of folks seem to recommend Rotella.  Do you know if it is any better than any of the other std oils?

[Stu Jackson]

"Favorite" and "best" oils, Ken, is almost like asking about the "best" anchor.  It's just one of those things where each skipper has his favorite that works for him.  Many love their Rotella.

[Ken Juul]

I totally agree with you Stu.  Jeff's in the business, his opinion might carry a bit more weight.

[Jeff Kaplan]

ken, the most popular brand is shell rotella 15w40, the industry standard. if it is recommended for a 525hp cat engine, trust me, we can use it in our little 3 bangers. i use delo, chevron,  sae30w as mentioned above, because i don't need a multi vis. oil.  for those of you who enjoy a longer season and want a multi grade oil, go for rotella, if its available, if not i recommend a high quality, brand name oil or, as ron  mentioned,mobil 1 syn. oil. but remember, if you use synthetic oil, stay with it...jeff

[Jeff Kaplan]

one thing i forgot to mention, which may be obvious or not, when buying oil, especially at an auto parts store, read the container just to make sure you see the words,for use in diesel engines. you'd be surprised how many brands are not diesel approved, meaning of course, for gas engines only. for what it's worth...jeff

[Albreen]

Cruising World magazine just happens to have an article in the March '09 issue re: choosing an oil. See link:

http://www.cruisingworld.com/how-to/maintenance/choose-the-right-crankcase-oil-1000069397.html

[Hawk]

Jeff/Stu,

As I said earlier, out west where the boat is in the water year round, the standard oil used is 15W40 specified for use in diesal engines. Also you want to check the API Seal rating on the container to be sure, as I said, that the oil is rated as one or more of CF4, CG4, CH4, CI4. The lettering has changed over the years. The cruising world article above explains it.
Hawk

[mainesail]

I think it's much more important to use a diesel specific oil, or "C" rated oil, not one made for gas engines with an "S" rating.  Sticking with a brand (additive package) is also somewhat more important than to worry about mixing weights.

This is conventional Rotella T 15W-40 at 2800+ hours of engine use..


Valve cover un-cleaned and as removed:


You don't need to over think this. Wal*Mart is the low cost distributor of Rotella T in 15W-40. While your engine will take either a diesel grade 30 weight or a 15W-40 you won't have as much luck these days readily and consistently finding a straight 30 weight diesel grade oil. When you do it will be more expensive than Rotella T 15W-40 from Wal*Mart..

[Albreen]

Wow! I doubt I would get the same clean look if I pulled the valve cover on my 1300+ hours engine. The PO used conventional 30W oil - I continued with the same the past season. I think these pictures just found a convert. 

[Ron Hill]

Guys, Susan & D : The biggest problem that the early Universals have is that you can not get all of the dirty oil out !  Seems that the oil drain is in the front of the oil pan and to make things worse the engine is tilted back.
The newer Universals have the oil drain in the rear of the engine.  If you ever have your M25/35A  engine out of the boat - move the oil drain to the rear and put a plug in the front drain.
The largest difference between a "C" and a "S" rated oil is how that oil & additives suspend the dirty particulents.  That's why it's important to use "C" rated oil in a diesel.  Both grades oil lubricate, but it's the "C" additives that better suspend the dirty stuff (learned that from a Mobil engineer). 
A few thoughts.

[Stu Jackson]

Don't use only "S" oil.

Use "C" rated oil.

Read Cruising World's latest Steve D'Antonio, nothing new there, but he does mention it.

Engine Oil Basic 101.

Read the bloody label.

Please.  It's YOUR engine.

[Jim Hardesty]

As long as we are talking oils.  What are the thoughts on additives.  I have used Lucus products and been very impressed in other applications.  The sales story that I believe is that most wear happens at start-up.  With no oil pressure the only lubrication is what ever oil is left on the surface.  It's believable, but it's hard to tell, our engines will last a long, long time with just average maintains.  I haven't started using an additive in my new to me boat, but am planning to this season.  I could change my mind if others have had problems.
Only about 2 more months to make that decision when I restart the engine.

[Albreen]

Ron and all,
As stated by Ron, my vintage C34 has a drain plug forward with the engine tilted up leaving residual oil in the back of the pan. In order to convert to Rotella T, do you recommend dropping the pan to remove this residual volume and letting all the oil drip out of the engine as well? I realize you should not mix both types of oil.

Also, I've heard the superior cleaning ability of synthetic oil (evidenced by the photos) may cause other issues in an older engine, e.g., leaks in seals and cyclinder blow by (reducing compression) when all the gummy plugs in the engine are very well cleaned - as in it cleans too well. Can anyone comment?

[mainesail]

Ron and all,
As stated by Ron, my vintage C34 has a drain plug forward with the engine tilted up leaving residual oil in the back of the pan. In order to convert to Rotella T, do you recommend dropping the pan to remove this residual volume and letting all the oil drip out of the engine as well? I realize you should not mix both types of oil.

Please lets not over think this. If you want to get rid of that residual oil or seriously dilute what's left, you can simply do two oil changes. This beats dropping the pan down for sure. Mixing an S & C with 95% of it being C is far better than using 100% S rated oil.

Also, I've heard the superior cleaning ability of synthetic oil (evidenced by the photos) may cause other issues in an older engine, e.g., leaks in seals and cyclinder blow by (reducing compression) when all the gummy plugs in the engine are very well cleaned - as in it cleans too well. Can anyone comment?

If you want evidence with photos look at the photos in post #22 above. Again this engine has 2800+ hours of run time with CONVENTIONAL Rotella T and looks like brand new. How long will it take you to get to 2800 hours, 10, 15, 20 years or more?? This engine has NEVER had even one drop of synthetic oil in it nor any additives.

I bought into the synthetic thing big time years ago. Most of my cars were converted with 80K miles or so on them. Within weeks of conversion I would always have major oil leaks. When I say "leaks" it was usually more than one so I know it was not just a coincidence. Synthetic oil makers say this does not happen anymore but I personally don't buy it with an older engine. Unless you are converting shortly after break in why risk it when conventional oils will work perfectly in a small aux diesel? Rotella T 15W-40 is a great oil and needs no additives to take a marine engine to well over 2800 hours and keep it very clean..

On thing I do before winter is to do the double oil change. One new filter but a double oil change with a 15 minute run in between. My engine burns zero oil and consumes none between changes..

Sailboat engine deaths can usually be blamed on short run times that never completely burn off start up condensation. If you want to prolong the life of your engine focus on your engine running times...

P.S. My brother commuted from Maine to Boston for years in a Honda Accord the car finally wore out, rust killed it, with 325k miles but not the engine. The engine was still going strong and had only ever had conventional oil put in it. Oils are so good these days that engines just do not wear out anymore..

[Albreen]

My error - I thought Rotella T was a synthetic oil and the photos showed the cleaning results due to its use. I reread the thread and it does say 'conventional'. Regrets..........