motor oil companies

[kenwood guy]

ok with that said which oil is the best??? I use 20W-50 penz-oil on my old 91 caprice 203,000 and still runs good non Synthetic by the way

[timberdoodle]

mobil1 is most often chosen because it uses no viscosity improvers. Most over the counter oil products do the same thing, synthetic is proven better than regular dinosaur juice because it stands up to the thermal breakdown much better, actually you can go for up to three times the amount of time between oil changes with synthetic.

Also as a tip, if you arent going to get a synthetic, it is best to get oil with the shortest span of viscosity. For example 10w-40, and 5w-30 use more polymers than a 10w-30 or 20w-50. So a better choice would be the 10-30

[Doug Rodrigues]

When NOT to use synthetic oils:

1. Don't use synthetic oil in an engine that is rarely started! Unlike mineral oils, synthetic oils will slowly migrate to the oil pan after a few weeks which will result in a "dry start." Aircraft engines which use synthtic oils will often have a pre-oiler in the form of an aux electrical oil pump, or an oil pressure reservoir that will pressurize the oil passages just prior to cranking the engine over. If they don't have the pre-oiler, the engines have to be started at least one per week. Automobiles don't use such a system. Otherwise, synthetic oils do give the best lubrication.

2. Don't use synthetic oil in a high time engine that leaks or burns oil. If you have an oil leaker or an engine that uses a lot of oil, you may as well leak or burn the cheaper mineral oils.

3. Depending on what additives you've been using, some additives create a gunk inside the engine walls that slough-off if synthetic oil is used. Depending on what contaminates are caught in that gunk, using synthetic oil may be like freeing dirt...or whatever, to ruin your bearings. Of course most oil additives are worthless anyway. Go ask any shop that specializes in engine rebuilding about the gunk that they occasionally see from people using additives. Engine manufacturers tell you to NOT use oil additives.

*Just my from personal experience.

[CrzyMR2T]

Originally Posted by 83-944

Oops, that's the wrong link. There are two synthetic motor oil types (in general). One is hydrocracked mineral oil ie Castrol Syntec, Quaker State Syn, Rotella T. Basically it breaks the larger molecules of oil into smaller even sized ones. It gives syn oil properties at a cheaper cost. Then there are "true" synthetic PAO oils. Refined from the beginning w/ small molecules. Also PAO oils are polarized, meaning they tend to stay in place after the engine stops. Much better for cold startups.

Small molecules = better smoother, even flow.

so are mobil 1 full syntec oils hydrocracked mineral oil?

[83-944]

Mobil1 isn't hydrocracked
Castrol syntec IIRC is

[kenwood guy]

how about that restore stuff oil additive it is said to restore compression across all cyls.. is that true or will that gunk up my engine??

[Holyterror]

Yes, Castrol is hydrocracked, but still a high quality oil. Mobil 1 is probably the best you will find off-the-shelf. Amsoil is my preferred lube.

This topic has been discussed over and over again, so I'll try to focus on info not mentioned in other threads.

Rotary engines and synthetic oils don't mix, at least not in their current form. In a Wankel rotary, the nasty sludge that forms when mineral oil burns is what protects and conditions the apex seals (the rotary equivalent of piston rings)! Synthetic oils burn cleaner, hence they do not leave this critical residue behind. Unless your engine is constantly put under a lot of stress, it will take a long time for you to notice the difference, but after 60-75k miles, the apex seals will be ready to let go if you use synthetic oil. Hopefully, better seal design will eliminate this issue in the future.

It is also noteworthy that mineral oil and PAO synthetics do not form water emulsifications like other synthetics do. However, they float on top of it, displacing it to the bottom of the crankcase where it will likely be scavenged into the oil lines. Water in the oil supply is bad no matter how you slice it, but I thought I'd mention this little-known fact.

[CrzyMR2T]

how much are amsoil? how do you get them? im thinking about using mobil 1. my friends in the air national guard, and he saids that they use mobil 1 for their airplanes, i think its the c130 hercules.

is valvoline hydrocracked? my brother uses that company.

between hydrocracked, and true syntec, there must be enough difference for it to matter then? what are all the ups, and downs?

[83-944]

You can order amsoil off their website or search of a distributor from there too.
www.amsoil.com

Holyterror: thanks for the rotary info. I was looking for a reason why.