Hey everyone I’m new to this forum and the proud owner of a 93 kingfisher blue xj40. The man i purchased it from was using 20w50 is this what most of you are using? Cheers
Hello Elizabeth/Sam (!). Yes, I also run Castrol GTX 20/50 in my car and always have.
It’s the best oil for these engines.
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Agreed, its the last of the old engine. 20/50 ifyou have valvoline vr-1 they have additives such as zinc .
It cost more but WELL worth it.
gtjoey1314
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Thanks for the great feedback!
I run 15w40 in my XJ40 and X300 cars. My 1994 XJ40 carries about 78psi of oil pressure going down the road and 40psi or so at idle (after the engine is warmed up). BTW, I can confirm these readings because I have a mechanical oil pressure gauge installed in the car rather than the OEM no-numbers gauge.
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Steve , Not to get off track, Using a mechanical gage on the x300 IS A TRUE READING.
The factory x300 gage is a dummy except for very early cars.
The factory was not happy with a bouncy needle so they changes the sending unit to the dummy read.
xj40 was still old school.
20/50 unless real cold then 10/40 just to spin a hair faster…
Thats 12 xj40 and xj300 owned or worked on…
Great cars…
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It wasn’t so much that Jaguar was unhappy with the moving gauge but more unhappy with the failure rate (and warranty claims) of the sending units. The solution was to go with Ford engineering and use a sending unit that put the needle in the center of the gauge as long as there was minimum oil pressure present. A clear indication of the cheapening of the product which many customers objected to when their cars were upgraded. GM on the other hand stuck with a gauge that read actual oil pressure. I believe I read on a forum that there is a GM sending unit that will work in Jaguars.
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Aftermarket senders work fine, some need a resistor in series, some don’t.
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