I have never been convinced that multi weight oils are any better than straight weight oils. The claim is that multi weight oil resists changes in viscosity as the temperature changes, I think that is all B.S. I have used straight weight Penzoil in every engine that I have ever owned for almost all of my 60 years on this planet and never had a problem. I do of course make sure it is detergent oil and meets the manufacrure specifications. I change oil every 2500-3000 miles in my vehicles and I usually put 150,000 plus miles on them without any problems at all. I put 418,000 on a 71 F-100 with a 390 in it and it was still running very good when I sold it. Lets hear some arguements!

 

[updated:LAST EDITED ON 08-Jan-03 AT 03:13 PM (EST)]mantta ..... I agree with you, I aways used straight weights my self.


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Many years ago I had a 1949 Ford Customline. The sticker inside the glove compartment door had the oil recommendations on it. It stated that at temperatures below -20 degrees F to use 4 qts of 10W oil and one quart of kerosene.

 

I suppose if you live in a mild climate, then straight-weight oil is OK. Twice this year it has already dropped to 10 below zero in my neck of the woods. That straight-weight oil can't be doing my engine any good if it's thick as caramel, sitting at the bottom of the oil pan. I would agree that you can go too far on the multi-viscosity thing; 5W-50 would have to be mostly chemicals and very little oil. I'm thinking 10W-30 is a must here in the Arctic, considering we only have 6 more MONTHS till spring!

 

I'd like to see this question asked in Oil and Lubrication section, I'd bet that there would be a lot of disscusion on this topic.

I like the multi weight for it's cold weather starting ability, especially in the minus digits.

 

I don't see why anyone would use straight weight oil in any enigne with the current technology out there. Might try posting this in the oil and lubrication forum. You will get much better responses there. I can't see why you wouldn't want your oil to be thinner at cold temperatures and the same as a straight weight at warmer temps.

 

Ratsmoker, that is the big deal, I do not know of any liquid, including oil, that gets thinner as the temperature decreases. In the petrolium industry it is called viscosity. I will bet that if I tood a glass tube say 2 or 3 feet in length, filled one with 10W-30 and the other with straight 10W, in a temperature of say 15 degrees, and dropped a BB in each one at the same time, the results would be the BB would reach the bottom of the tube first in the tube of 10W oil.

 

I belive you have that incorrect. The "W" in 10W-30 means "winter" that is the weight when cold. A more accurate to life comparisom would be to test 10W-30 agenst 30 weight oil in cold weather, unless you change weights of oil with the seasons. And i'm sure 10w-30 is better than 30 in cold weather.

 

At freezing 10W30 is the same thickness as 10W. At hot temps it is the same as straight 30W. Oil gets thinner with temperature increases no matter what grade it is but multigrades won't get as thick when cold as straight grades. This topic really belongs in the oil forum.