I've had 20W-50 in my car since I rebuilt the engine. Haven't driven it much this winter as I don't take it out when it is shitty. I'd bought a case of 10W-30 oil back before Christmas and have been thinking about changing the oil as it has about 1500 miles on it, this would be the 2nd change since I rebuilt. But with warmer weather likely just around the corner, should I just stick to 20W-50?

 

The 20w-50 is good for temperatures above 20 degrees. So if you think you will be running in temps colder than that I would use the 10W-30.

 

When you say case, you mean 12 right?

I would just use it. Summer is not quite here yet and since it wont be a while til we see some 80+ daily, i think that 10w-30 could be put to good use right about now.

Then again, i been running 10w-30 since i owned the car, winter and summer. But i never drive long trips so.

 

I run 5-30 in winter, never had to use 0-30 as it doesn't get colder then high 40's here. Spring and fall I run 10-30 and in the peak summer then I use 15-50 Red Line or 20-50 Amsoil. I have been using Castrol GTX dyno oil since my last rebuild though.

 

Just run it...IMO 20w50 is not needed unless extremely hot ambient temps or tracking the car (or making 400 rwhp.....with stock oil cooler).

 

10w30 was a poor performing oil compared to 5w30 a few years back, I doubt the add pack was changed to be more comparable to 5w30 so I stay away from 10w30, ymmv. I also don't know why the 10w30 was engineered so poorly, perhaps an auto manufacturer spec'd it to cut down on additives to fill their motors with cheaper oil.

 

Are you sure that was 10w30 and not 10w40? I have not seen test that have shown that, but I have seen tests showing the issues with 10w40.

 

You may be right, I am no longer working for one of the major oil additive manufacturers and I'm basically out of the oil business these days so memory is starting to fail me.

 

i use 20/50 alll day nvr had a prob butt hen agin its just oil..ive tried synthetic RP never reallysaw a diff

 

Yup - you remembered it correctly. Some of the viscosity extenders in the 10W40 dino oils would break down quickly and leave you with something like 10W20 after a few 1000 miles.

Dave