Can I get away with having 20W30 oil in 28 degree weather for a few days? I知 usually in sunny San Diego but I知 in Sedona AZ for a few days.

 

Personally I would have no issue with it but give the car a couple minutes to warm up.

You risk oil starving critical surfaces if it won't flow....but i can't imagine it is THAT cold in Az.

 

Does the car have a block heater? I'd plug it in for 45min before you want to start it. Even in warm weather a 20W oil is fairly heavy.

Years ago our local car club had a oil chemist come out from the Esso ( Exxon) research center and talk about oil in cars. His recommendation was use the lowest possible first number, so the oil flows fast upon startup, and then use the second number as whatever the car maker recommends.

For example, if the manual calls for 10W40, he said to use 0W40. This reduces cold start wear ( which is where 90% of an engines wear occurs) and it gives the same hot protection.

 

SAE spec says that 20W oil is suitable down to -20F so worrying about +28 is pointless.

 

? 0W should be good to -45 or so. Or do you mean 20W?

 

Yes, meant 20W. Thanks for the catch.

 

Jagboi64 comments from the Esso chemist are very pertinent & correct.
Why are you using 20W/30 oil ?
May I suggest you are guided by the Tech Bulletin 12-58 attached.

John Herbert
(MY96 XJR)

 

My mechanic advised me the same; am using 0W30 on my XJR.

 

I've mentioned before that the "old timer" mechanic at my local Jaguar dealer that does all the service on the older cars recommends 20W50 all year in our area where temperatures normally range from 10-20F to 100F.

He says the AJ16 is not much different than the the previous AJ6 which specified 20W50, and Jaguar began specifying lighter weight oil with increased fuel economy requirements when the AJ16 came out.

He saw quite a few issues with chain tensioner rattle when owners stuck with the lighter weight oils, especially in warmer climates and also especially if they didn't use the OEM oil filter.

I've done quite a bit of testing myself with oil weight and non-OEM filter combinations, and in my experience it appears he is correct. For me 0W40 oil for example will cause the tensioner to clatter in warm weather.

But even if one doesn't feel comfortable with that recommendation, the attached table shows that 15+Wx is good down to freezing, and 10W is good down to -5F.


YMMV

.

 

That was a typo. I meant 20W50.

 

The engine may crank a little more slowly than in San Diego, but as long as your battery is healthy you should be fine. I ran 20W50 in our XJ40/AJ6 year 'round in Tennessee with winter temps rarely below 0F, and only changed to 10W40 for winters in Indiana when our son started driving it to college.

Cheers,

Don