Where in the handbook does it say not to?

For hot climates (Such as San Antonio, TX) it is my preference to use a slightly thicker oil.

 

Castrol GTX 5w30 here, with a WIX filter or oem one, just depending on where is convenient.

 

Just because a Manufacturer recommends an oil, filter, etc doesn't mean its sacrilege to use another brand. Example, Mitch is wise to use a 40 weight oil as its hotter than hell in Texas. Just as someone that lives in the the northern tier should use a 0W for cold starts which is killer on motors. Those of us in the temperate world just need 5W-30.

 

I use Mobil 1 and Castrol synth 5W-30 interchangeably, depending on which is on sale at change time. Awhile back, I heard there was a problem with the quality of Castrol synth and it still bothers me, but I have heard nothing about it in quite awhile. I like the Purolator standard filter but would use any good quality filter. I used to use only Jag filters but got tired of chasing them around and decided any good brand filter would do. After much research, I determined that the quality of the base oils in Amsoil is one class better (class III) than Mobil 1 and Castrol but the high price drives me away. If I were racing, I would use Amsoil though.

 

I won't argue the high price of Amsoil, but since I typically average 12K miles/year, which is well below what Amsoil recommends for oil change mileage (1 year/25,000 miles), I end up changing oil once a year, changing the filter every 6 months and topping off.

 

As I understand it the Jag filters have one way valves which is one reason I wouldnt use aftermarket.How would you know if they had one too?

 

I don't know of ANY aftermarket oil filter offered in the US that doesn't have an anti-drainback device, although there might be as I haven't personally tried every single filter offered for the AJV8. One of the most popularly quoted aftermarket filters on this forum is the Purolator (L15317 for the 4.2L). I am holding one in my hands as I type. The third feature listed on the package is: Anti-drainback valve - minimizes engine dry start (which is a mis-statement in itself). This filter, as well as several other aftermarket ones are perfectly fine for these engines.

The Jaguar filter is fine too, but some people just object to the high markup. Also keep in mind, Jaguar does not make oil filters. They use one of these very aftermarket companies to supply them with the Jaguar logo on it. Just gets down to what you want to pay for.

 

I do not see anywhere in Jaguar handbooks/manuals/specs that a synthetic motor oil is required on this car?
In fact 2 dealers said to stick with regular as that is what it left the factory with, am I missing something her?

 

Nobody uses the Jaguar oil filter?

 

Well, I suppose I do, because I just had the local Jaguar main dealer service my car.

 

The cynical side of me says of course they want you to stick with regular, as you have to change it more often.

I've used synthetic (Amsoil) in my vehicles for 15 years. I change the oil yearly (because I never reach the mileage limitation), and the filter every 6 months. I've never had a problem. Amsoil advertises a 2-5% increase in fuel economy. As well, if you only change the oil every year (or 25,000 miles) you dump less used oil back into the environment.

As usual, ymmv. Use what you are most comfortable with.