Ok, so I'm about to do my first oil change on my 1988 Jaguar XJ6 with 3.6 engine. I went to Autozone and bought an STP 2995 oil filter for $6.49. Then I asked them what their computer says for oil. They told me my car takes 8.5 qts of 20W-50 synthetic! I went to many different places in town and most don't even carry that weight of oil! Finally I found a 50% off special on Valvoline Racing Oil Synthetic something something.....20W-50. It was originally $9 per quart! I got it for $4.50 a quart and I have 9 quarts sitting in a box in my garage now. I JUST got my Haynes manual for my car this morning. It says that my car takes 10W-40? Can anyone tell me what oil I should actually be using? Regular or synthetic? What kind of weight? I don't mind using synthetic since it's such an expensive engine and it won't be used for long trips therefore I don't plan on changing oil that often. Also for what it's worth.....I live in Indiana where our winters can on occasion drop a little below zero degrees and in the summer we can reach a high of 102 degrees as a max. I obviously don't plan on using it or even starting it in temperatures below 15 degrees.

 

In my experience, for what it's worth, the weight of oil that you would use is largley dependant on the climate conditions of the usual location of the vehicle.

From what you say about your climate I would happily put in the 20-50 oil you have purchased. For what looks like a good price BTW. I have 20-50 in the 92.

Don't make the novice mistake, that just because the car does not make long trips then you don't need to change the oil that often.

Quite the opposite is true. Short trips = more wear on the oil. Plan on changing it every 12 months or around 3-5k miles if you can.

As a general and not too technical rule, the lower the first number in 20-50, 15-40 etc the lower the ambient temperature range for the oil.

In the Jaguar manual that came with the car, a whole range of oil specs are given depending on climate.

Just dug out a Haynes, and yes it does generically specify 10-40, but it does not give climatic variations.

 

Thanks for the reply. And that does make sense about the need to change the oil routinely even if not going long distances. I'm going to start a good log book for this car and I'll buy that oil whenever it comes on sale each time. My friend is the store manager of an autozone so he'll let me know. I just didn't want to put too thick of an oil in and mess it up. Thanks again so much!

 

using 20/50 is no problem in the summer months, as it has a higher viscosity and is less prone to breaking down. If there is a problem with it is in the colder months it will have more drag on start up. therefore that why most manufacturers recomend lighter weights in the winter.

 

stay with 20-50 for that engine. Jaguar designed it around that oil. I used 5-30 for a year cause I get it at work. But kept getting alot of startup chain buzz. I sswitched back to 20-50 and it when away. The newer vvt engine are built around 5-30 till they wear and start having vvt malfunctions, then a thicker oil is needed at that point