Here is my experience with Rotella and the 235 engine in my ’53 truck. For 10 years I have annually changed the oil using RotellaT4 (Dino) 15w-40. No appreciable oil use, no noticeable leaks and good oil pressure. Last year I mistakenly picked up RotellaT5 (semi-synthetic) for the annual change. During the summer, I noticed slight seepage around the lifter cover and under the manifold. Coincidence? Last month. I changed oil again, this time ensuring it was Rotella T4 (dino) and for good measure I added a quart of Lucas gasket treatment additive. Its been less than 200 miles but the engine has remained dry, and the oil pressure is even better, remaining at 3/4 to pegged even at idle.
