Mixing Oils

[Goosen]

I accidentally poured 1/2 quart of straight 30W with 6 quarts of 10W30 while changing the oil in my '91 Previa. Will this damage the engine? (Castrol GTX)

Goosen

 

[patprimmer]

No, though not recomended, 1/2 quart will not damage your engine, especially when it is the same brand and type of oil, just different viscosity

Regards
pat

 

[rudyhiebert]

Something to keep in mind is that your engine would not be as protected in extreme cold temps compared to when the engine oil is consistantly 10W-30. In my situation I needed to finish filling with my synthetic after I changed oil using 10W-40. I was fresh out so just used a half a quart of 5W-30. I'm sure I'll be fine until next time.

 

[evelrod]

Good grief. We are sure 'gitten' picky here. I'll just bet that even a chemist would have a hard time finding that 1/2 qt. !!!

Rod

 

[patprimmer]

Well I am a chemist, and I gota agree with Rod here. Well I always find it hard, and dangerous, to dissagree with Rod.

1/2 Quart will make a barely measurable (with precise scientific equipment), and certainly not noticable change. Only possible risk, and so low as to be virtually no risk at all, is for incompatibility with additive packages. That is why I say mixing oil is not recomended, but same brand and type, how muck risk can there be. I think none at all.

Regards
pat