Keith O,
The difference between auto 30w and Diesel 30w is the chemical makeup. But the short story is diesel has less detergents and more ZDDP (zinc). Auto's are nearly all roller vavletrain now and require less zinc (the slippery stuff in oil) and ZDDP and catalytic converters don't get along well so oil manufacturers have been required to remove most of it from car oil.
Diesels on the other hand still run flat tappet stuff and much higher vavletrain pressures that require more ZDDP than autos ever did. And since most are not required to pass an "emissions" tests, all the good stuff stays in. On a side note, you will find that nearly all new diesels require a seperate EXHAUST fluid that gets passed through the converters to burn out the build up of the good stuff in the oil.
Most lawn and garden oil still has a high enough ZDDP count to work well. But the bottom line is diesel oil is better "oil".
Next time your buying oil, look at the little API stamp on the label and see what standards the oils meet. There will be a lot of letters on the auto oil and only a few on the diesel. So don't put diesel oil in the minivan unless you want to replace the cats.
I run Lucas SAE 30 Plus oil. It is specifically designed for the flat tappet, air cooled, low detergent type engine we use. It works great and is made right in Corona CA, USA. Another side note, I also use 2oz Lucas Upper cylinder lubricant and 2oz Lucas Ethanol treatment in every 5gal can of 87 octane I use for my cubs. It runs like a top and has noticeably more power, faster revs, and less noise than when I run out of those things.
Jonathan D,
Here's why the full synthetic oil is ALWAYS better. Imagine all the little carbon chains we call oil floating around in a Qt of oil. When that oil comes from dinosaur oil, there are lots of different chains of all different sizes. For the sake argument, let's say they are golf balls, baseballs, and soccerballs. All the little golf balls do nothing but fill space. Yes the lubricate, but they are small enough to slip past rings, valve guides, seals and just quickly get burned up or get stuck somewhere they shouldn't be. All those soccerballs are even worse. They are to large to even really properly lubricate and mostly get broken up or never make to the tiny spaces we call clearances. It's all those baseballs that do all the work we want, lubricating while stay where we need them.
Full synthetic oil is engineered to be ALL baseballs (all the exact same carbon chain and all the same perfect size). Its still oil, it's just engineered and formed in a lab instead of under a pile of rocks we call earth. So you are already noticing the benefit of full syn oil. Because you are no longer burning off all those golf balls and breaking down those soccerballs (becoming sludge) which is why Dino oil is so high in detergents, to keep those broken down chains from sticking to your engine parts, which ironically means its passing more dirt and less oil through the oil passages the longer it's run. Why do you think they make full syn's that can run 15k miles? It's not breaking down or burning up!
