Mixing Oil Weights?
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Mixing Oil Weights?
I have one quart of Rotella 10W-30 left over from winter. I'm getting ready for summer and was getting Rotella 15W-40. Can I put in one quart of 10W-30 along with 14 quarts of 15W-40? I'm not really even sure what those numbers mean other than the thickness of the oil. Thanks. Joe.
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I wouldn't say it's "never" a good idea, in a pinch wouldn't think twice. Bob Pirsig in his Drive It Forever book (Bob was an SAE guy) said that mixing weights is OK provided the resulting (averaged) weight is acceptable for the temperatures being operated at. A quart of 5w-30 with four quarts of 10w-30 is just going to result in a viscosity somewhere in between the two. What is not necessarily OK, mixing different brands of oils (even if of the same weight viscosity) that are derived from different major base stocks, like say a Pennzoil and Castrol, something like that. Paraffin based oils are actually very good but tend to gum up badly if regular maintenance is not performed, short trips, etc.
Last edited by Tedster9; Mar 18, 2007 at 03:51 PM.
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From: Bossier City, LA
Originally Posted by Tedster9
I wouldn't say it's "never" a good idea, in a pinch wouldn't think twice. Bob Pirsig in his Drive It Forever book (Bob was an SAE guy) said that mixing weights is OK provided the resulting (averaged) weight is acceptable for the temperatures being operated at. A quart of 5w-30 with four quarts of 10w-30 is just going to result in a viscosity somewhere in between the two. What is not necessarily OK, mixing different brands of oils (even if of the same weight viscosity) that are derived from different major base stocks, like say a Pennzoil and Castrol, something like that. Paraffin based oils are actually very good but tend to gum up badly if regular maintenance is not performed, short trips, etc.
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