Multi weight oils. Good info.
 

I have recently been doing a lot of research on engine oils. Ive had to many dock and bar room discussions on oil, and decided to spend some time reading up. We all talk about zinc content, and other minerals and additives, but.....theres more to it than that. During all these late nights of reading and reading, I started noticing something common in all these write up's, that was common.

Its about the use of multi-weight oils. Apparently, in conventional engine oil, in order to develop a multi weight oil, they must use ''Viscosity improvers". Lets take a 20W50 oil for example.

The oil must flow like a 20 weight oil at 0* Fahrenheit , and a 50 weight at 210*. Problem with oil using viscosity improvers, is that they don't do well with heat and or high load/shear situations, and eventually break down. When the oil does break down, it no longer resists thinning at temperature, and therefore that 20w50, may act like a 20w20, 20w30, etc at 210* after a few hours depending on the situation.

Some articles I've read from oil engineers, is that if a multi viscosity oil must be used, try to use one with as little visc improvers as possible. Meaning, a 10w30, or 5w20, will have less than say a 20w50, or 10w40.

With that being said, synthetic multiweight oils do not suffer from this. As the makeup of the oil doesn't need the viscosity improvers like a conventional dino style oil. Probably why you see synthetic 15w50, 5w50, etc. Plus they say the synthetics hold up much better with heat and do not break down as easily.

To sum things up, I have read enough on this subject, to myself go back to using a straight weight conventional, without viscosity improvers. My boat engine oil will never see 0 degrees Fahrenheit, not even 32* Fahrenheit. Most day's im boating the pan temps will be ambient at startup, which should be anywhere from 75-90*. The 20w50 I was using, at those temps, probably isn't flowing like a 20 weight oil anyhow, since it was tested to flow like a 20w at 0 degrees. I know there are a lot of builders out there still recommending straight weight oil for marine engines. I just never knew why they would recommend that.

I am going to attach a couple articles on this, for those who may wish to read for themselves. Grab a cup of coffee or a cold brew and check it out.

Very good read. Covers a ton about oil.
http://hrcak.srce.hr/file/37720

http://www.enginebuildermag.com/Arti..._slippery.aspx

Mild

As I have said on different oil threads that for the Past 30+ years I have used straight 40 w Racing oil in all my boat motors Most of them Blower motors without any Lower end Failures, the boat I have now is going on it's 14th season this year withoout any oiling problems. So with that said I'm 100% backing your findings with real world results.

Thanks for getting the info out to the members!

I agree with you on stright weight racing oils for our boats, I use Dino but synthetic is fine if you want to speed the coin.

That's some great information Wild Mulder!

What oil you gonna run ICPPLSDIKS?

Good stuff buddy. I'd like to see a oil viscosity test done on say a 20w50 at 100* Fahrenheit. We know what it is a 0* and 210*, but what about in the middle?

Interesting.... I always noticed that when running 20w50 after putting a few hours on a fresh oil change the oil pressure at idle after a long run would progressively diminish. Semi synthetics seem to perform better than straight dino and I always assumed this had something to do with viscosity deterioration due to heat. My solution has been to top the oil levels off with Lucas heavy duty oil stabilizer as needed which has worked pretty well for me.

MILD THUNDER great post!

Im shocked at how poorly Royal Purple performed

The idea of relying on additives (visc improvers) to protect and do their job, just scares me. In my particular engines, the idea of 20weight oil at 6000rpm under boost and heat, doesn't excite me. maybe I'll send in a sample of my Brad Penn 20w50 with about 10 hours on it, for a oil analysis to see how it held up viscosity wise.