What is the best oil for the Jaguar V12?
I realize that I am opening up a can of worms with this post and that everyone has their favorites, but based on my experience and research, I have selected the oil that I will use moving forward with this engine…….here goes.
I bought into the benefits of synthetic oil early and was using it in all my cars when I purchased the Jaguar in ’98. Right away I put Performax Synthetic 5W50 (not sure why I chose that weight) in the car. For the next three years, I changed the oil with Mobil 1 synthetic 10W30 and twice with Syntec synthetic 10W30.
During this time, I put 9,000 miles on the car and it had started to leak pretty noticeably. I read that synthetic oils could be bad for old gaskets and seals so I changed to conventional oils from that time on.
My current project to replace the bottom end gaskets has made me re-examine the decision to change back to conventional oils.
I think the primary problem is that most of my driving is short trips. Converting back to synthetic oil will definitely clean things up…….but I still have the original rope rear seal and crankshaft front oil seal. I am sure these will start to leak if I run synthetic oil long term.
Also, I have decided not to do an engine flush, as this could aggravate the seals, but will put the car on a diet of even more frequent oil changes with a high detergent conventional oil.
I have been using Castrol GTX 20W50 for the last 5 oil changes over 8,000 miles with the results that you see above. After much research, it seems the conventional oil with the best detergents is Pennzoil yellow bottle . This is the oil I will use moving forward.
Replace plug and then remove oil filter. Add some oil to the new filter and to the new filter gasket. Hand tighten until it makes contact and then tighten another 3/4 turn. Fill, run engine and check for leaks. Check level a couple of times after driving to make sure you have enough oil after it has a chance to settle in the oil pan.
I will pull the oil pan after a few thousand miles and check for sludge buildup. Watch this space for updates………