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Author Topic:   OIL QUESTION
HarrisMod#30
Dirt Freak

Total posts: 384
posted December 23, 2005 05:19 PM  
What is the differance between a 15w50 synthetic and a 20w50 synthtic oil? Is any of these two better than the other?

stockcar5
Dirt Forum Champ
Total posts: 602
posted December 23, 2005 06:32 PM  
the 15-50 is thinner than a 20-50 when cold. some guys run the thinner stuff in the spring then switch to a 20-50 for mid summer.

i myself run 15-50 mobil 1 all the time. royal purple is very good also.

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rocket36
Dirt Freak

Total posts: 246
posted December 23, 2005 06:33 PM  
cold start up viscosity.
basically, the 15W is thinner than the 20W on start up when the oil is cold. both oils will be similar, 50, at operating temperature.

that is a very basic explanation, but pretty much sums it up. there is a lot more science involved than just that, but don't worry about it.

HarrisMod#30
Dirt Freak

Total posts: 384
posted December 23, 2005 08:34 PM  
ok thanks, motor just recommended 15 50 so i should be good with 20 50!

James Ott
Dirt Maniac

Total posts: 185
posted December 24, 2005 06:38 PM  
W" means winter or very very cold sub freezing cold. not cold oil in the summer cold. There will be slight difference in the viscosity at the cold end should both end up at the same or close to it at the hot end. Another thing to consider is that low number is the "true" viscosoty of the oil and high number will be the result of the additives. So as the oil begins to break down the 20W50 will be that slightly longer. Either will work and yup Rocket you are on the money. Amsoil is good

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