Roj wrote:
...I don't have any actual test data to prove I'm right. By the same token, no one has any test data to prove that I'm wrong either.
Roj
hmm...i should do some testing soon i think
lesson learned for everyone to remember READ THE SPECS and go from there...
if anyone doesn't understand the specs here's some info...
http://en.wikipedia.org/wiki/Engine_oiland...
Quote:
All about engine oils
by Jim Kerr
Changing the engine oil in a car today seems increasingly complicated. Pull into a quick-lube and they ask if you want a regular, premium, synthetic blend, or full synthetic oil. As soon as you make a choice, they bombard you with questions about the grade of oil you want: 10W-30, 5W-30, 10W-40, and so on! Finally, you get to select the brand. Answer all the questions and get a cup of coffee as a prize.
Even more complicated, try selecting the right engine oil off the shelf at the local store. Rows and rows of oil containers have basically the same shape, but check out the fine print on the back of one and you will find a mind-boggling sea of information. There are API (American Petroleum Institute) classifications such as SH, SJ, CF-4, or CH-4. It may say it is "energy conserving" or that it meets military specs. Many say they are suitable for turbochargers, and almost all meet car manufacturers specifications. So what is best for your vehicle?
Checking your vehicle owner's manual recommendations is a good starting point. Most vehicles can use a regular oil. If these oils didn't meet manufacturer's specs, they wouldn't be on the market. Premium oils are often a higher quality and slightly higher priced because they start with better quality oil when refined, or have more special additives to help protect your engine. Energy conserving oils have more friction reducing additives. Synthetic oils are usually only specified for high performance cars, but the ability to flow easily at low temperatures and still protect engine parts at very high temperatures make them beneficial for any vehicle. Their only disadvantage is their substantially higher price. A few engines, such as Ford's Powerstroke Diesel, require special oils. This engine needs an oil with lots of anti-foam additive to prevent air bubbles forming in the oil-charged diesel injectors.
Viscosity refers to the oil's ability to flow. An oil with SAE (Society of Automotive Engineers) grade 5W-20 flows easier than a 10W-30 oil. The lower the number, the easier it flows and the easier a cold engine cranks over, but low viscosity oils don't protect engine parts as well. They become too thin at higher temperatures. Most manufacturers specify 10W-30 oil or 5W-30 oil for year around use in most areas of Canada.
API classifications are easy for passenger cars and most light trucks. Choose an oil with an API "SJ" or "SL" rating. The SJ rating was established in 1997 and is good for 2001 and earlier vehicles. It set new standards for deposit control, oil oxidation, engine wear, and corrosion protection. It supercedes older SF, SG, and SH ratings. SL oils are the latest designation and are designed to decrease oil consumption even lower. You will find some oils also meet CF-4, CG-4, or CH-4 specs. These are usually designed for heavy-duty diesel truck applications.
Do we need engine oil specifically designed for higher mileage engines? Market trends would indicate we do. Canadians are driving their cars more - an average of 17 - 18,000 kilometres per year. Vehicle durability has improved and vehicles last longer. In the 1970's, vehicles lasted 150-160,000 kilometres. In the 1990's, proper maintenance provided engine durability an average of 260-280,000 kilometres. Engine life is projected at being 320-340,000 kilometres for this decade's engine designs.
Engine leaks are one of the top five automotive warranty concerns. Engine oil specifically designed for high mileage vehicles has a special seal conditioner additive that penetrates the pores of the seals to make them seal more effectively. Better sealing of the valve seals reduces oil consumption past the valve guides and better sealing of crankshaft seals reduces external leaks.
As owners keep their vehicles longer, maintenance becomes even more important and regular oil changes are part of that care. Many auto manufacturers recommend oil changes at 12 to 15,000 km intervals. Better engines enable oil change intervals to be extended. However, extreme cold, high heat, dusty conditions, and short trip driving all qualify the vehicle for the severe maintenance schedule in the owner's manual, which includes more frequent oil changes. Oil Life monitors on many GM, Mercedes-Benz and BMW vehicles calculate oil life based on heat, load and rpm's. Oil change intervals are based on actual needs rather than time or mileage intervals.
There are scores of engine oils on the market. Many of the differences are in the proportions of additives in the additive packages. Detergents are added to clean internal engine parts. Pour point depressants help the oil flow at extreme cold temperatures. Anti-foam additives lower the surface tension of the oil molecules to reduce oil foaming caused by violent churning in the crankcase. Corrosion and rust inhibitors protect engine parts from harmful blow-by products.
Many oil producers do not recommend mixing different brands of oils because of their different additive packages. If an owner is going to change oil brands, an oil change is a convenient time to do it, however, if you need to add oil don't worry if you can't find the same brand. I have never seen an engine fail because someone mixed oil brands but I have seen many fail because they were low on oil. Check that engine oil level often.
Jim Kerr is a master automotive mechanic and teaches automotive technology. He has been writing automotive articles for fifteen years for newspapers and magazines in Canada and the United States, and is a member of the Automotive Journalist's Association of Canada (AJAC).
ciao