Recently moved to Iowa, and am expecting colder winters than I am used to - single digits Fahrenheit and negatives on occasion. Looking in the manual, should I switch to a lighter oil, maybe 10w30 if I expect to drive in winter, or would y'all recommend sticking with 20w50 and just letting it warm up longer?

Thanks!

 

For sub-freezing conditions I'd go with 10/30 or 10/40. My experience is the engine will labor to turn over on cold starts with 20/50

Cheers
DD

 

What part of Iowa? I live in the northwest corner. This will be the first winter for my 72 XJ6 and I'll be using the 20/50 GTX Classic. We'll see.
Let us know what you decide to go with.

Hopefully we can meet up some day. I'm a member of the Iowa British Car Club which is based in Des Moines. Two and a half our drive for me but worth it. Check out the club.

Jeff H.

 

We had a presentation at the local car club from an oil engineer from Esso ( Exxon in the USA). His recommendation was to have the first number be 0 in cold weather, and the second number be whatever the car manufacturer recommends. For a XK engine 40 is a good weight, so I would use 0W-40.

The reason for the 0 is about 80% of an engines wear occurs on startup, so you want the oil to be a pumpable quickly on cold start. The faster the oil can get up into the engine from the sump, the less wear there is.

If you look on the Mark 1/Mark 2 forum here, Glyn Ruck is a Tribologist (oil engineer) for one of the major oil companies and he has some posts about what oil to use.

 

I'm in Des Moines! Do you have contact info for the club? I found them online but both the email address and phone number seemed to be out of service. I'd love to meet some folks in the area.

 

The club is on Facebook. Try there. In the mean time I'll try to track contact info down. Apologies the web site is out of date.

Jeff H..