XJ6 & XJ12 Series I, II & III 1968-1992

1986 xj6 correct oil

Old 06-22-2014, 11:50 AM
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Default 1986 xj6 correct oil

Hello what is the correct oil and weight to be used for a 1986 xj6 with under 80k miles? Car will not be driven in the winter. It has been sitting for some years and don't remember what was used in it last

I have the 4.2. Also how many quarts?

Last edited by 86xj6; 06-22-2014 at 11:54 AM.
Old 06-22-2014, 01:07 PM
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20/50 is the usual favorite for the old "XK" engine series. IMHO any name brand will do; nothing exotic required. Some have a sentimental attachment to Castrol GTX.

Since almost all on-the-shelf oils these days are low zinc, adding ZDDP or other zinc replacement additive surely wouldn't hurt although there's some debate as to the actual real world neccessity or benefit.

I recall that you'll need 9 quarts but put in 8, start engine, wait for oil pressure, stop engine....and recheck after letting it sit for a few minutes. Earlier Ser IIIs take one quart less than your '86 car....but I can never rember if it's 7 quarts vs. 8 quarts or 8 quarts vs. 9 quarts.

Old 06-22-2014, 01:53 PM
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Doug it is 8.5 qts., at least that is what it is in my '84. 1986 should be the same.

does the poster have the Owners Handbook for his model year XJ-6 ??

I use Castrol 20W50 because when I bought my first Jaguar centuries ago, I went around Jaguar shops asking questions and 3 Jaguar techs told me to use nothing but Castrol oil in the 4.2 engine.
Old 06-22-2014, 04:04 PM
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Thanks a lot !! I love the people on here always so helpful
Old 06-22-2014, 05:32 PM
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What's the thoughts on 10/40 semi=synth??
I know you're not supposed to use fully synthetic because of the rear crank seal, but read somewhere that semi-synth was ok.

Suggestion from the Castrol website

Your selected vehicle
Model Daimler Limousine 4.2 (Daimler)
Engine P
Year 1968-1992
Your engine oil recommendations
Engine (P)

Capacity: 8.2 (ltr)

EDGE 0W-40 A3/B4


Last edited by anjum; 06-22-2014 at 05:34 PM.
Old 06-23-2014, 06:52 AM
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synthetic is thinner oil, loves to leak out, and Jaguars do not need any help with leakage. stick with Mineral oil.
Old 06-23-2014, 07:07 AM
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Thanks could not remember which to use.
Without a lift can be real bugger to get to the plug
Old 06-23-2014, 07:17 AM
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the oil drain plug? I use the tire jack to raise the car enough on one side, then place a safety jack stand under the wishbone and shock mount, remove the plug, start to drain, remove the jack stand, lower the car again so all the oil comes out, then repeat to remove the oil filter (very messy), and then reinstall the plug.

you can use the lugnuts wrench to remove the drain bolt-plug. (assuming it has not been replaced with a smaller head bolt).

SAFETY FIRST: always park the car on a level surface, emergency brake fully tight and transmission in PARK, these cars weigh over 3,000 pounds and you don't want it collapsing on you.

Last edited by Jose; 06-23-2014 at 07:28 AM.
Old 06-23-2014, 07:56 AM
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Both my cars are powered by 94 power plants. 20-50 has been my oil of choice for various critters over decades. I like Valvoline aka Carquest. usually good deals there. but, any dino oil is fine for older engines.

Were I to have a newish plant, I might go the synthetic route.

But for my present cars, I don't see the cost/benefit.

I do live in a moderate clime. But, if in a cold clime, I'd consider a different viscosity.

I've a built in bias against the low viscosity oils because of a misadventure early on in my grease monkey career.

Old 06-11-2017, 03:05 AM
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While an old thread, I was doing a search on the oil capacity of the 4.2 XK motor as the mouse stopped in the wheel for some reason and this came up.

Been away from all of this for years living abroad with out car! I'm just getting back into it all.

Anyway, thought I would add..

Yes, I too was partial to Castrol 20/50 (vis a vis sentimental) .. and 20/50 was always the oil recommended for the XK engine.

I have owned most models from the MK2 forward ..well actually Mk7..

Anyway, FYI, those in the know use and highly recommend .... diesel engine oil.
...for a variety of reasons I won't get into now...it's late!

But it is ideal for our old engines. Resists breakdown retaining viscosity like no other, resists heat, gunk buildup, etc.
I intend to use nothing else anymore. do some research..

WalMart for around $26 for a 2.5 gallon jug. (8.5Qts)

Mobil Delvac 1300 Super SAE 15W-40 Heavy Duty Diesel Engine Oil

FWIW to ya..
kind regards.

PS: Do NOT use synthetics in XK or other older engines...just change it regularly..it's all that is required. Older engines require oil changes more often anyway. I always had done it very often...like 1500miles depending on motor's age/condition and how often driven until we developed a rapport.
I generally went by time as much distance btw changes.
Compression never lost a point and motors never let me down. fwiw

Last edited by Demian; 06-11-2017 at 03:28 AM.
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