Oil Type questions

Hello, I have some questions on oil again . Every year I seem think I should be using something different, so just want to check with you all. The 2 motors are '94 454's with about 860 hours on them. I've been using shell rotella straight 40 and I havent had any problems at all. I am in Boston, and alot of my friends are using a 15w-40. People say the benefit of the 15w - 40 is for colder starts. I'm not really doing much boating when its colder than 70, except for hauling out, winterizing, spring commisioning, etc .

My crusader book says use 40w, so I've stuck with that, and the Shell Rotella with NAPA 1515 filters. Should I just keep using it or make a switch? I notice the Shell Rotella 15w-40 is usually cheaper too. I have 3 gallons of 40w now that is probably enough to do both engines for my fall changes. I'm thinking maybe do one with that and switch the oil in the other motor? Or just wait until next fall and switch it all

thanks!

Variable viscosity oil--that makes life easy for distributor/ oil pump drive gears--is a miracle of modern science. Why on earth would anyone not use it?

Jeff

OK, so will this work? Motor Oil - Shell - 1 Gal, Shell Rotella T Triple Protection HD; 15W40 - Part Number: SHE 550019913. My local NAPA will let me exchange the 40w (Part Number: SHE 550019858) for the 15w-40, so I think I will.

thanks

I used to run straight 40 in my 454, I was a florida boater with about 80 deg avg start up temperature. It was ok, got around 1500 hours out of overhauled engines. Then, I read an article that really made me think as an engineer. ONE: run the thinnest oil you can, but still maintain oil pressure at the hottest engine temperature. SECOND: Run the highest API oil weight spread you can to get best cold, startup oil flow (like fast jeff says). All being equal 0W40 is better than 10W40. Even a 0W oil is far thicker at 75 degrees than you want at startup. A straight 40 takes "forever" to flow into your 2.5 thou main bearing shells. So, to get oil to do that trick of "multi-viscosity" the oil needs viscosity stabilizers added. As I understand it, synthetic oil stabilizers last longer than mineral oil additives. So, if you want the best cold start lube performance, that tells me use a synthetic, like a 0W-30 (tight 454-close bearing clearances), or a 0W-40 (if you can't keep good engine pressure hot). In theory, as an engine ages, the oil viscosity you feed it should increase. Maybe more than you asked for here, but that's my understanding of the basics of engine lube, ignoring several other issues, detergents, cost, oxidation, anti-wear ingredients, ....These big V8's are old school design. Meaning, they have some high sheer moving parts, cam/lifter/oil pump to name a couple areas of concern. More modern designs have roller lifters, etc in an effort to be less demanding on oil and let it last longer.

I too would use Rotella 0W40 IF that made it. Unfortunately, they are stuck on making only 15W40.

Jeff

Thank you all. I went with the shell rotella 15w40. Only put in about 6qts but levels seem ok. My friend with '96 454's used Mercury 25w 40. Interesting the different things people recommend. Which is why I'm asking here . Thanks again.

What makes it more entertaining is the number of variations, for oil recommendations, made by the OEMs, when the base engine is internally identical....I think the biggest driver in the variation is the perceived operating environment and its effect on warranty coverage....

Like DD suggested, we went to synthetics a long time ago...over 3000 hours before major overhaul....and that was with flat tappet engines...It truly is the only way to go.