Newbie Oil Question

Hello All,

Appologies if this has been answered before. I've searched the forum and found that 15w-40 Rotella is highly favored in our Jeeps. I'm getting a 1969 CJ5 with the 225 Dauntless engine. It is quite low milage on the engine - only 25,000. The original owner (an older gentleman) hardly ever drove it.

My concern is running 15w-40 in the colder temps here in Colorado. Will this oil be to thick and sluggish in temperatures approaching 0 degrees Farenheit? Can running too heavy of an oil cause any problems?

What do you guys living in colder climates run to keep those flat tappets happy?

Thanks in advance.

 

Thick oil in cold weather can make cranking too much of a strain on the starter/battery. And I suspect would not easily fulfil it's lubricating functions until well warmed up.

15-40SAE seems a little bit heavy for OºF, IMHO, in a low-miles engine.

On the other hand what will happen during a long run on a hot freeway in the summer?

I would go with what gives you reasonable oil pressure at hot idle, and at also speed, under local conditions.

 

The reason I use a diesel rated oil is.for the good levels of zinc. You can use a 10-30 diesel oil and still get the zinc protection (prevents camshaft wear for non rolller cams like ours) plus it will flow at colder temps. I had a distributor gear pin shear in my dauntless, so I have been sticking to 10-30 since then anyhow. I use Delo400 diesel oil as it has higher levels of zinc than Rotella but both are great oils.

 

In Michigan I have always used 10W 30, for year round oil. I now don't drive my Jeep in winter any longer, so I use 30w for the nine months I do use it, ride a sled the other three.

 

Thank you guys - that's just what I needed to know. 10w-30 Delo 400 it is!

 

I live in Colorado too, & I run regular 10W40 dinosaur oil (Valvoline)

 

I live in Mid-Arizona. 20W-50. 5 months of 99ºF as the low temp at night demands it.