What's the deal with oil ratings?

JohnnyG · 04-01-2002, 10:40 AM

I understand that the difference between 10W-30 and 10W-40 oils have something to do with viscosity, but what exactly do each of the numbers and letters mean? And which is ideal for which application?

John

Jeb_Bush_2000 · 04-01-2002, 11:01 AM

Multiviscosity oils are identified by their viscosity spread. 10W-30 is essentially 10-weight oil that becomes no thinner than 30-weight oil when heated to operating temperature. 0W-20 is 0-weight that doesn't get any thinner than 20-weight when heated. Lower numbers are better suited to lower cold-start temps. I doubt you would ever need 0-weight oil in Maryland. Up nahth (

), however, it's probably wise to run 5W-something in the winter.

With organic oils, generally the wider the spread, the less stable it is.

04-01-2002, 10:40 AM	#1
JohnnyG Registered Member Join Date: Feb 1999 Location: Baltimore, MD USA Posts: 105	What's the deal with oil ratings? I understand that the difference between 10W-30 and 10W-40 oils have something to do with viscosity, but what exactly do each of the numbers and letters mean? And which is ideal for which application? John __________________ 1991 GT Vert- Black/Black/Black Exhaust, Tremec, Tri-Ax, Centerforce Dual Friction, 3.73's, Rear Seat Delete MM Road & Track Kit PBR 5-Lug Brakes Cobra R's w/ 255 Rubber Rice Hater's Club #60

04-01-2002, 11:01 AM	#2
Jeb_Bush_2000 Registered Member Join Date: Jul 2001 Location: Taxachusetts Posts: 374	Multiviscosity oils are identified by their viscosity spread. 10W-30 is essentially 10-weight oil that becomes no thinner than 30-weight oil when heated to operating temperature. 0W-20 is 0-weight that doesn't get any thinner than 20-weight when heated. Lower numbers are better suited to lower cold-start temps. I doubt you would ever need 0-weight oil in Maryland. Up nahth (), however, it's probably wise to run 5W-something in the winter. With organic oils, generally the wider the spread, the less stable it is.

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