97 Jag XK8, 73k on it it. Oil changed with Mobil 1 back in late march. Since then we have put about 3500 miles on the car. Should I change it now or can I wait alittle longer. Car gets driven thru this summer about 2 or 3 times a week around town. In a few weeks that will go to about every day of the week around town, to work. When should I change this oil? Oil is still clean looking on the dipstick, car is not driven hard.

 

. . . and then the fight started . . .

Jaguar says 10k, some say 3, 5, 8, 12k, or longer with oil test.

Have you changed your ATF?

 

Whatever you're comfortable with Tim. I started at every 3k, then moved to about every 4k. Would I let it sit for 6 months w/o an oil change? Me, probably not much longer if the target mileage wasn't reached. Don't even get testpoint started on the dino vs synthetic debate.

If you are using synthetic, drop mobil 1 and use Castrol/Valvoline/Pennzoil. I have heard several times about the weak shearing properties of Mobil 1. Even if it's not factual and documented, its not worth it to me to take a chance.

 

I love Mobil1, I ran it in a old Caprice cop car since they (the cops) had also ran it in the car and I beat the heck out fo the car, hot roddin it and so forth and when I sold it at 225k miles that motor was still tight, quiet, no oil burning or leaking, motor looked like it had 30k on it it it was so clean. So I am a believer of M1 I guess. I have usally went with about 4-5k betqween changes with M1 in that Caprice but this jag is not that car. Ha ha ha. Just want to make a smart decision.
As for changing fluid in the trans I was under the undrstanding that the trans in this 97 was sealed, hell I don't even see a dipstick for it, that the trans was typically one that lasted till 90-100k then expect it to need a overhaul. What is the story with these trans in the 97's I guess I need to ask? Right now mine does not leak, shifts well, etc....

 

Without a used oil analysis the allegations regarding shearing issues with our oil is baseless. A lot of factors have to be considered when making claims that an oil is prone to shearing etc. Driving style, maintenance habits and the condition of the motor internally. Do Mobil get some reports of shearing? Yes, they do. Does every one else? Yes, they do.

I would agree that with these 4.0l V-8 motors (N/A ans S/C) have a tendency to consume oil. With that being said, our 5W-30 syn. would not do so well in these engines. I would suggest using M1 0W-40 during the winter and 5W-50 for the summer months. It's kind of sad being a Mobil guy, I personally run Redline 5W-40 at 4,000 mile/6 month intervals and my car doesn't burn a drop. My car like your is the garage queen and see's the road 2-3 times a week at best. If anyone has any questions regarding Mobil products feel free to PM me

 

Matt,

It was Charlie Leonard, may he rest in peace, that was the dino champion. I haven't used dino oil in 25 years.

BRGJag,

I would suggest that you change the ATF. ZF now recommends 100k Kilometer, 60k miles ATF change on the 5hp24 transmission used in the XK8 '97 through '02. The 'sealed for life' was created by the marketing department during the warranty wars of the last half of the '90s. 'Life' should be understood to be the warranty period.

 

At 73k miles should I change it, trans fluid. WIll the new fluid in a old/used trans kill it quicker??

 

Yes, by all means, change it.

ATF loses its lubricating properties just like engine oil does. Lots of conversation about not using a power flush on a high mileage transmission, even from the flush equipment makers. But then, I have never found anyone with flush equipment that had the capability to change the ZF fluid.

 

No offense USDM, I was simply restating what I heard on more than one occassion. I wondered why the avatar got changed to the M O B I L today. Its good to have someone around that can answer oil questions such as the issue of shearing properties, and all I ask in return is that you can be objective and as unbiased as possible with your input. If it leans toward Mobil products, I can see that. You're position gives you instant credibility, I hope you are willing to share some of your material knowledge with the group.

 

@USDM-STi-FTW,

Why is it that you want to use higher viscosity oils, whereas that is not recommended by Jaguar?

I admit to be using M1 0w40 myself, which is already higher, and it was the HTHS value that made me go to this higher viscosity one (and the extra HP I have). But the Redline 0w40 and especially the M1 5w50 have even higher viscosities.

Andre.
´

 

Until recently I had been using Castrol Syntech, but recently switched to Castrol Edge. The choice was mainly for the increased wear protection rather than change interval. CE is not a cheap oil but it can be found at a reasonable price through places like WalMart. There are several other good oil choices available and the key is making sure the oil and filter get changed at an interval commensurate with the age of the engine and your driving conditions/habits. There is nothing to be gained from stretching out oil changes particularly in the supercharged engines employed in the XKs. The same can be said for the transmission fluid. Although the transmission fluid is not subject to combustion-related compounds it is nevertheless subjected to high temperatures, hydraulic forces and shear...all of which degrade the original properties of the fluid. In the larger picture of owning one of these great cars attention to motor oil, transmission fluid, brake fluid and coolant changes are the easiest things to do and they add significantly to sustained vehicle performance and life span.

Happy Driving

Tim

 

Jaguar actually recommends oil viscosities ranging from 5W-30 to 15W-40 depending on your climate conditions. Using 0W-40 in the coldest of winter months during cold start conditions will out perform ANY 5W-30 engine oil available while being able to attain a 40W viscosity when driving your forced induction, high horsepower, oil eating V-8 at operating temprature. xW-30 engine oils are simply prone to shearing under these extreme conditions, especially when it comes to these Jag motors. In your case, the above is even more relevent. You claim to have a 500hp XK, the motor is no longer seeing what the factory previoulsy tested the car as. The conditions of what is happening to your motor internally has changed and the oil is the only thing protecting it. What has been recommended by the factory is no longer accurate. Regarding the 5W-50, during the summer months. This oil will perform greatly. It has excellent cold starting properties and with the increase of heat the motor is making the added protection (if it even gets to that point) will be there. Realistically, the flow of a 40W oil is not all that much better of a 50W oil.

 

USDM, isn't it also that with synthetic oils, the weight rating is based on the " dino oil characteristics", not so much on the physical properties of the synthetic oil. I seem to recall reading that one time. What I mean by this is that the full synthetic oil may have a physical flow characteristics of say a 5W oil, but because it coats the metal like a 20W oil, it is given the 20W rating. I might be saying things out my butt. But, this is how come some of the synthetic oils can have ratings that are very wide.

 

The extra power has triggered me to closely follow the oil condition, and have done several analyses over the years. I have always used the M1 0w40 and oil analyses have always shown exceptionally well values. Oil consumption has also been acceptable considering the extra hp used (and thus more blowby etc), and was usually about 1 liter per 5000 km. This makes me believe that the oil is holding well (including engine), and thus believe higher viscosity oil under my usual driving conditions is not needed.
I only now checked my handbook, and indeed there is a recommendation for 10w-40 in climates until 50 degrees Celsius.
Then the 5w-50 viscosity might not be too far off as you say for areas where it gets hot but not right for my climate in Europe ;-).

 

Am I just stupid or what, I have choose to use the Castrol Edge 10W-30 in my 1999 XK8. I has a stated warranty from the mfg for a 15K change interval. With that warranty it covers internal oil failures. Castrol came out with this advance synthetic with the added change interval, and the warranty first. Then not to lose market share Mobil One was forced to follow suit. These cars cost enough to keep going why would you not choose to put the burdon of oil related failure on the manufacture with the warranty and not spend extra money on changing it every 3K or 5K. If you ask the dealer on these older models they only are using dino anyway.

So I guess the choice is up to you!