[GB SISSON]

Originally Posted by Flathead Fever

I was a fleet mechanic for 30-years. We were only allowed to use Delo 15W40 because we bought it in bulk form pumped into a 400 gallon underground tank. No matter what the under hood label recommended the engine got Delo 15W40 diesel oil. Small four-cylinders, generators on up to large diesels. I never saw a camshaft go flat. We never had any wear issues unless the oil all leaked out. We probably had a thousand vehicles and I don't remember an engine ever wearing out. They usually seized up Drivers were suppose to check the oil and we only serviced them every 6-months so you can imagine what happened. Sometimes those engines would go 12K miles between services. The vehicles always fell apart long before the engines gave-up. So that convinced me to use that oil in all my older cars. It has all the anti-wear additives you need for your flat tappet cams because the additives need to be their for the pressures placed on those diesel engines wear surfaces. The viscosity is great for cold start ups and warm driving. The modern engines that use "0W" and"5W" viscosity have really tight clearances in their engines. I don't know think I would feel comfortable using it in an older engine. Most of us stick with what we know has always worked until the government takes it away. And the other guy that mentioned Walmart is correct. You can buy 5-gallon jugs of Delo 15W40 cheaper there than any other place on the planet. In fact I had a neighbor that owned a oil change shop and he bought all his oil from Walmart.

I did an oil change on one of my flatheads a couple years ago and didn't use delo 15-40. I used Shell rotella T 15-40, another good diesel rated oil. Driving around with our favorite 'feel good' oil makes us happy even though many good ones are out there.