Do the old Atlas and Commandos need one? I figure it couldn't hurt.

We've ridden this subject into the ground, No they don't need one except in very dry hot conditions riding same direction as the wind. The amount of oil in circulation in Norton twin is not enough to really cool engine, maybe like 6% of total heat flow is via the oil, so only reason to cool it is if oil got much over 200' F which is the heat level needed to get the dry start protection of the famous zinc/phos ZDDP. Take rather over 160' F to cook off combustion moisture too.

If ya do, use a thermostat bypass and maybe even a leather cover for cold times like the HD twin guys use to keep oil temps up close to 200' F. If you can get your Norton oil in tank to read over 190' F in public I will shake you hand on such hard hearted WOT risk taking for over 50 miles to do so.

Hi

I have been running a oil cooler on my 850 for 35 years now, also had a oil cooler on my Trumphies and when I finish my 1961 Dommie it will have one as well, some say you don't need them but in my opinion I think a cooler is the go and the same with running good oil.

Ashley

I know oil cooler make all the sense in the world but have you measured your oil temps or looked into why ZDDP is on push rod air cooled minds and what it takes to get its protection? Most Nortons never had a cooler for most their lives yet it don't seem to bother them with a cooler, so can fly either way about as long and easy.

I have a Lockhart oil cooler, but I also installed a Jagg Oil Cooler Thermostat. According to the Jagg literature and my corespndance with the company, it begins to open around 180 degrees and will fully open at 195. I can reach down and touch the outlet side of the cooler when riding to see when it is flowing or not. While It does not come on often, this past summer it came on often enough to make me feel better.