oil change

[mpoulin]

Hello all,

I another post in this forum, people seem to appreciate 15w-40 as the oil to use with the Atomic 4. Shell Rotella seems to come up a lot. I have found this oil but looks to me that it is for diesel engines. Is that the case and people use it anyway in the A4 or is there a 15W-40 for gas engine?

I am changing the oil on my A-4 for the first time and have no clue as to what went in there with the previous owner. Engine runs great and I would like to give it the best in oil.

Thanks for advice,

cheers,

Maurice
1968 A-4, all original!

[hanleyclifford]

The 15-40w is normally thought of as diesel engine oil because diesels have more stringent requirements than gasoline engines. I use the 15-40w in warm weather because my engine is loose and had low oil pressure after sustained running at cruise on long trips. In the winter I use straight 30w high detergent. For me the choice comes down to usage and general condition of the engine. If your engine has steady oil pressure (30-40 psi) after sustained use you will be fine with straight 30w.

[ndutton]

Primer on oil API codes:

http://www.pqiamerica.com/apiserviceclass.htm

FYI, A-4 specification calls for SJ or CH-4 API rating.

[Bratina]

I run Rotella 15w-40 on Lake Ontario - we're in water between late April and late October. I get 20lbs at idle, and 40lbs warm at cruising RPMs. I change oil 2x a year, and it's usually clean when I extract it (via the dipstick and a vacuum extraction pump).

[edwardc]

I have been using 15W40 "diesel oil" for several years, and have been quite satisfied with it. My rebuilt FWC engine runs at 180 deg, and when fully warmed up the oil pressure sits at 35 psi at cruise (2000-2200 rpm) and 23-25 psi at idle.

One practical advantage I've found with 15W40 is that while out cruising on the Chesapeake Bay, many of the smaller towns we visit do not carry straight 30W oil, but they all have 15W40 diesel oil.

[romantic comedy]

i dont see the point for running a single viscosity. Modern oils are quite good. The multi viscosity oil provides for better starting and less wear doing so. I know that many times the engines are not warmed up before a load is put on them. Also with raw water cooling, warm up is even longer. IMHO

I run 10-30, 10-40, whatever seems good at the time.

[Mo]

15w40 for mine...for years now.

[ndutton]

More on motor oil. Hopefully we can get out ahead of the misconceptions before they're presented as fact.

http://themotoroilevaluator.com/members-blog/understanding-multi-viscosity-oils/#axzz4AaR4qzir

[hanleyclifford]

More on motor oil. Hopefully we can get out ahead of the misconceptions before they're presented as fact.

http://themotoroilevaluator.com/memb...#axzz4AaR4qzir

Interesting tease, that link...so did you sign up for their "course", and how much did it cost?

[ndutton]

I posted that and the previous link for general information regarding lubrication oils. It's all about good information. Maybe we can learn something along the way.

Since multi-vis rating was suggested in a previous post as being for diesels, here is another link regarding diesel ratings, identified with a "C" in the API code.

http://www.oilspecifications.org/api_eolcs.php

[Mo]

http://www.drivenracingoil.com/news/dro/training-center/articles/zinc-in-motor-oil/

[romantic comedy]

A long time ago I went to a lecture by an "oil guy", not sure from which company. He explained that there were polymers that were heat activated and helped the oil not thin as much in high temperatures. He used a spider analogy where the spider is curled up at low temperatures and as the temp increases, the spider extends it legs to increase viscosity.

He went on to talk about film thickness and all sorts of interesting facts about oil. I cant remember much, but I concluded that multi viscosity oils were fine, if not superior, for all applications that I might come across.

[mpoulin]

Thank you everyone!

Oil is changed, new plugs, new filter, I am hooking up batteries tonight and will start-up the engine for a test!

Boat is heading into the water Saturday!

Cheers,

Maurice