Think with your dipstick, Jimmy! - Castrol EDGE

Ivan Seeking

Back when I was knowlegable about the automotive industry, there were high-quality oil brands, and then there was the low-grade stuff. One could tell by checking the SAE ratings. I am told that today there is very little difference between any two brands of oil; that the only real choice is whether to use natural or synthetic oil.



Do we still need to think with our dipsticks, Jimmy?

Ivan Seeking

I said SAE rating, but I meant to say the API rating.

Also, feedback regarding natural vs synthetic oils would helpful.

turbo

For a while, when I was selling mechanical seals, pump packing, etc, the company carried the Royal Purple line of lubricants. RP supplied us with test machines with which to demonstrate the superior lubricating properties of their synthetic oils. There was a cantilevered arm with a counterweight on it that pressed a ball-bearing (hard!) against a rotating shaft. Mineral oils would break down and smoke in short order, while the RP protected the bearing for much longer times and under heavier loads. The only oil I tested against the RP that was as good or better was Mobil One - another synthetic.

When I was running a Harley with fairly steep cams, I went with Aeroshell - a synthetic with additives and detergents designed for airplanes. I did not test Aeroshell against RP or Mobil One, but that would have been a good test.

chemisttree

That machine would be the Scuffing Load Ball on Cylinder Lubricity Evaluator (SLBOCLE or ASTM D6078, D6079) I used to sell a product like that in my own shop. Came in an orange 12 oz bottle. You were supposed to use it with an 'oil cleaner' in your oil change. The oil cleaner would suspend grit, soot, varnish, etc... and (after changing the oil) the additive would be added to the engine after the fresh oil.

I did it on my own car once. It started leaking oil from the front and rear shaft seals right after that.

Synthetics make better base oils than naturals IIRC, but the cleanliness of the oil and the additive package trumps all that. Dirty oil without those additives is no good so a synthetic oil left in an engine too long is not much better than using a natural oil and changing it more frequently . Of course you will have a lot of $ left over to change the oil more frequently if you use a quality natural oil vs. the synthetic.

Ivan Seeking

Another consideration would be the environmental impact of each option.

chemisttree

Hmmm. I'm not seeing the environmental advantage to synthetics over natural unless you believe that used oil finds its way back into the environment... most is recycled, I think. Synthetics have a pretty steep environmental price in their manufacture but I don't know the details of that.

turbo

It's probably effective and economical to run standard engines on the oils recommended by the engines' manufacturers. I dumped HD oil and went to Aeroshell for my Wide-Glide in part because aviation oils are designed to deal with some temperature extremes. Other factors included the higher lifter-to-cam pressures with steeper cams and the very high compression heads I was running. The engine would practically stall the starter on the compression stroke, and I never found anybody who could kick-start that beast, so multi-viscosity oil that didn't get thick when cold was pretty important. After I switched to Aeroshell, lifter pump-up time was minimal and starting was much easier.

Ivan Seeking

I don't know about our newest car [Tsu drives that one], but for the older one, synthetic oils are listed as optional.

Ivan Seeking

A couple of items in the news:

http://www.getg.com/index.php

http://www.safety-kleen.com/products.../EcoPower.aspx

turbo

Interesting. When I had a Corvair that used oil like crazy, I bought reprocessed oils in 2.5 gallon cans because they were cheap. Sapphire and Fox-Head were the two most common ones in '74. Forget about Corvair's safety record - their environmental record was terrible. The engines were designed with external push-rod tubes, and the O-rings that "sealed" the ends at the block and the heads would fail and blow hot vaporized oil all over the place, including the hot exhaust headers. It was all I could afford at the time until I could save up enough money to buy something that a normal person might want to drive. The price of the Corvair was low simply because nobody wanted it.

skeptic2

Many years ago Mobil 1 had an ad in Scientific American in which they claimed that the reason Mobil 1 was better than ordinary motor oils was that being synthetic it had a much tighter range of molecule sizes than ordinary oil. They showed two graphs of molecule sizes, both bell curves. The one for ordinary oil was low and broad and the one for Mobil 1 was tall and narrow. They said that because of the greater number of large molecules in ordinary oil, it tends to thicken more in cold temperatures and the greater number of small molecules reduce the lubrication and burn away faster.

Then again, it was just an ad.