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Saturday, August 05, 2006


Motor oil - conventional, synthetic, and snake varieties

It's time to give the Focus and the CX500 their oil changes.

Now, there is a lot of hype about motor oil out there. Some of it is the work of hucksters trying to make a quick buck. Here's a way too long list of companies busted for making dubious claims about their oil additives. But I think some of it may just be because of how long cars last these days. You just don't see many oil related failures unless there is something out and out wrong with the engine oiling system, such as the infamous Mitsubishi 4G63 problem with "crankwalk" - more precisely, the thrust bearing wearing out from not getting enough oil. Unless you're in the habbit of driving cars to the 200,000 mile mark, you may not even be keeping them long enough to tell if the oil has done anything. Unless you regularly have your oil tested at a lab, which these days can be done at a reasonable cost.

There are some cases where I've heard credible accounts of the wrong oil causing problems. They're often along the lines of having a problem develop after adding the wrong oil, only to have it go away once the owner put the right oil in. One very common example - although it's not quite motor oil - is that many '90s era Chrysler automatic transmissions are known for having problems if you accidentally put Dextron transmission fluid in them. Or you may notice that some sorts of oil make for a bit of sludge in your engine and others don't. But it's hard to tell if an engine that lasted to 160,000 miles would have lasted to 240,000 if you used a different brand of oil.

On the other hand, there are real differences in oil quality. Bob is the Oil Guy explains how oil additives can help make an engine last longer. It's worth noting that most oils already have these if they are API-certified. And I've seen dyno tests showing that synthetic oils can improve horsepower. I've decided this time to put some of Wal-Mart's cheap synthetic oil in the Focus. 5W-30, as the manual specifies.

Motorcycle oils are a special case. They often use the same oil for both the engine and the transmission. Many bike dealers will claim you need special oil for them. On the other hand, a test by Motorcycle Consumer News showed that high end car oils often seem to do better than motorcycle ones. And they cost a lot less than the premium they charge for on motorcycles. I have heard that the thinner automotive oils with the Energy Conserving mark often cause motorcycle clutches to slip.

Since I didn't want to spend the cost to fill the CX500 with Mobile One, I've opted for Shell Rotella T in 15W-40. This oil is made for diesel semi-trucks, but I've heard from motorcycle forums that it seems to work well in bikes too. And it's cheap.


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