Michael Sachs (“The Jag Doctor”) is the owner of Sachs Automotive, Inc. and has been working on Jaguar cars since 1989. He is a former member of the Jaguar Master Technician Guild as well as an ASE Master Auto Technician and the official late model technical expert for the JCCNF. 

First, let me start by saying this article is more informational than technical. During the last 5 years or so we have seen a huge rise in major oil leaks in the V-8 Engines. Now some of you will say a Jaguar with oil leaks, no way! Sorry I couldn’t resist.

The fact is that since the introduction of the XJ40 in 1988 oil leaks for the most part are all but gone. I have been trying to figure out why we are seeing so many rear main oil seal leaks, front timing cover gaskets, and valve cover gaskets leaking, especially since the gasket material as well as the system in which they are applied to engine components have been greatly improved.

We should be seeing fewer not more leaks. So, what’s changed? The oil change intervals, that’s what! The oil is staying in the engines so long that the oil its self is damaging the seals and gaskets. If you remember from a past article, I explained about all the contaminants that are in old oil. Also, the oil becomes acidic.



My customers that are either on 3 to 5-thousand-mile oil change intervals don’t seem to have as many problems. I have said from the beginning of the V-8 engine in 1997 that extended oil change intervals would cause excessive engine damage. The use of either conventional or synthetic oil doesn’t matter, the contaminants in the oil is the problem, so CHANGE YOUR OIL OFTEN.