oil numbers?
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Racer
Joined: Jul 2001
Posts: 341
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From: macon, ga
oil numbers?
okay dumb question of the day. what do the numbers on oil mean? i know that when i changed my cam the instruction say run 30wt. (which i am) but the oil cap says use 5-30wt. so what is the differance between 30wt. 40wt. ect. and 0w-30wt, and 5w-30wt, 10w-30wt. ect. thanks
Le Mans Master
Joined: Jul 1999
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From: Sewell NJ
Re: oil numbers? (ykp53)
I'll take a shot at this one but I may be a little off. On a straight weight oil like 30, 40, or 50 weight the number indicates the thickness of the oil. On multigrade oils like 10w-30 the first number indicates the oils equivalent flow capability at cold temperatures and the second number indicates the oils thickness at warm temperatures. In this case the oil would flow like a 10 weight oil when cold and protect like 30 weight oil when hot. If I'm wrong please chime in.
Race Director
Joined: Dec 1999
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Re: oil numbers? (vettfixr)
the weights refer to the viscosity of the oil. A higher weight oil is thicker than a lower weight.
A 10W30 oil is a 10 weight oil that has a package of viscosity index improvers (VII) that allow the oil to thin out NO MORE than what the weight of a 30weight oil would be at high temperature. So at high temperature the 10wght would be as thick as a 30wght at that temp.
Marck
[Modified by Twin_Turbo, 6:47 PM 1/15/2003]
A 10W30 oil is a 10 weight oil that has a package of viscosity index improvers (VII) that allow the oil to thin out NO MORE than what the weight of a 30weight oil would be at high temperature. So at high temperature the 10wght would be as thick as a 30wght at that temp.
Marck
[Modified by Twin_Turbo, 6:47 PM 1/15/2003]
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Re: oil numbers? (vettfixr)
I'll take a shot at this one but I may be a little off. On a straight weight oil like 30, 40, or 50 weight the number indicates the thickness of the oil. On multigrade oils like 10w-30 the first number indicates the oils equivalent flow capability at cold temperatures and the second number indicates the oils thickness at warm temperatures. In this case the oil would flow like a 10 weight oil when cold and protect like 30 weight oil when hot. If I'm wrong please chime in.
