I'll chime in for statistical value. I bought my X with 65K miles and no maintenance history, but it ran and sounded good, so I bought it. I put Mobile 1 full synth, (6.5 qts of 5W-30) and Mobile 1 filter at every oil change (3K miles). The car now has 120K miles, and it zips up thru the high rpms like a dream.

The X doesn't have a whole lot of torque or power at the wheels, but I get her up to 6K rpms now and again and it sounds great, runs great. I would never mix synth and dino oil, chemically these are two different animals as far as particle size and uniformity.

I will mention one thing about oil filters, don't use a Fram! An Internet search will bring up articles on the trouble with Fram oil filters. There's a lot of info on the subject.

As others have said, I buy the 5.6 qrt jug of Mobile 1 and an extra qt to top off up to 6.5 qts total in the engine. I have a slow oil leak, but I have an old mat under my car in the garage to catch the drips. The leak is super low volume and the headache of a new oil pan gasket is just not in the cards for me. I imagine I'll take my X to 200K miles, and then, if she's ready, I'll put a V8 under the hood and switch her to rear wheel drive, Lol.

 

Ooops sorry. I wrote I got the Extra Guard filter, which is the cheap orange one, but I actually got the Fram Tough Guard filter (the grey one) which is supposed to last 10,000 miles. I was looking around and realized Fram didn't get such great reviews but saw the Tough Guard and it sounded good. I think for my next filter I am going to go with K&N, I can get them on ebay cheaply if I plan ahead before I do my next oil change. So far the car's been driving great with the new oil and filter. Feels like a new car. I wish I had changed it about a month ago if I had known how big of a difference it would make. Highly recommend the Castrol GTX High Mileage if your car is getting up there in miles and is starting to drip.

 

And the joint runners up are ...

But, tonight's overall winner is ...
To which the crowd roared "And we don't think we ever will again!"

For what it's worth the Mk1 in my avatar, had over 120,000 miles under it when the engine was stripped down, and crankshaft and both camshafts measured in the toolmaking section of the local Small Arms Factory. Mains and all camshaft journals were all within original Jag tolerances, and big-ends had worn only half a thou on thrust axis only. Bore and piston wear was far more significant. Block was bored for wet sleeves, larger pistons, over 10:1 compression. Head replaced with ported and polished XK150S gold top head. Camshafts replaced for faster, longer, but not higher lift. All new standard bearings fitted.

With modified SU carbies, and straight through exhaust, and after 120,000 miles, engine is uprated from 2.4 to 3.0Litre capacity but otherwise all original crankshaft and rods. Over the next 6 years, we put a further 250,000 miles on that car with no further major overhaul, except for dropping the sump to replace the oil pump, to bring oil pressure back up to 60lb. Throughout that 350,000 miles we fed it Castrol oils (but I don't remember which) as per the handbook recommendations.

The three practices that I believe are far more important than "which oil" ...

1. never cheat on the time or mileage intervals for oil/filter changes, nor the manufacturer recommended viscosities, ratings;
2. never remove any engine cap until meticulously cleaned - this includes all drain plugs, fill plugs, dipsticks etc;
3. never refit a drain plug without re-cleaning all parts and replacing the sealing washer with a new replacement part.

No offense intended anywhere, but what else is there to get excited about?

Best wishes,

Ken

 

Hahahaha! Thank you all for this honor. It was a close one, we all did our best but in the end there could only be one....

 

Ah- but wait! There's more!

https://www.jaguarforums.com/forum/x...esults-112840/

Miracles abound. Who knew.

 

OK ... I give up.

 

I'm so disappointed I came in as a runner up I think I will go drown my sorrows in some beer. I promise to try harder next time.

 

Synthetic beer? It's much much better I hear.