How high is high?
oil generally won't affect OT to a noticeable degree.
I have an 85 gti with 280k that was running 20w-50 when i bought it. After a few months i chamged the oil using 10w-30 instead. Now im noticing high oil temps. Its been warmer lately and the coolant guage reads normal....any ideas? Im gonna educate myself on oil in the meantime. Thanks
And why would you put such a thin oil in a high mileage motor? I wouldn't go any thinner than 10/40.