Crikey !! I agree…will work…fine save $12. I will continue to use major brand engine oil. I am not so sure tho about your use of “perfectly”. It will work adequately. The savings on cheap adequate oil amounts to the LEAST one will ever spend on these cars: an amount differentially undetectable from zero.
Nick
If you want to geek out on oil there is a very informative YouTube channel called Lubrication Explained.
He has a video or two on ZDDP.
I am.
I’ve rebuilt thousands of engines, from very expensive race motors to many, many street engines.
I’ve never used anything else except off-the-shelf, brand-name oil, and that includes my 9800 RPM Datsun racer. That one I used 2050 Valvoline racing oil, changed once a season, filter every race.
I stand by my experience.
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dogs with bones…I certainly said…agreed, whatever will be ok…use cheap if you like…I would like to think that the largest brands, with the most money, with big labs…come up with something…but maybe they just buy lake houses and yachts. I guess I could be pithy…and ask…why so many rebuilds…?? but I won’t.
Nick
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Go right ahead … I know you want to! 
Do you recall me referencing my career as a professional mechanic? A career that extended essentially from the time I was eight years old till the time I was about 33? I had a lot of business… and NONE were returns because of oiling issues.
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I couldn’t possibly argue with that!
Now, about your taste in hamburgers… I tried my first Five Guys yesterday. We can discuss that in a different thread…
You sure you didn’t go to Sum Yung Guys"? 
Awwwww…What the hell. The more the merrier. I’ll chime in
I’ll be merciful and keep it short, though.
Must be close to 25 years since I got my first Jag; the first of four. One XK engine, one AJ16, two V12s. Three have been daily drivers. One a weekend driver. I reckon I’ve covered at least 200,000 miles in Jaguars. Probably more like 250,000.
In the early days I was very fussy about motor oil …and just about everything else. After a few years, and increasingly since, I found myself becoming rather nonchalant. I decided that all the fussiness was making me feel good but the car really didn’t seem to care one way or the other. So for about the last 20 years I’ve been using whatever motor oil was on sale that day. Whatever horrible things were supposed to happen just…haven’t happened.
I’m not sure if any of us could go out an buy an off-the-shelf motor oil that was so bad, or so far out of spec, that any actual engine damage would occur.
I’m sure that some oils are better than others in some ways and give better long term wear protection. I’m just not sure how many miles we’d have to drive our Jags to realize that actual benefit. 100,000? 150,000? 200,000? How many here accrue that kind of mileage?
My present daily driver is a V12 with over 200,000 miles. I change the oil every 3000-4000 miles. I keep a supply of ZDDPplus on hand for all the musclecars I work on (that’s another story). Sometimes, on an “Oh what the hell” basis, I’ll use it when I change the oil on the V12. Other times I don’t. If something bad is supposed to happen as a result of the not adding it, well, it ain’t a-happenin’ . Not, at least, in any way that I can hear, feel, see, touch, smell, or measure.
I’m not saying my practices are the best nor advocating that others follow suit. Just tossing in my 2-cents.
Do what makes you feel most comfortable. Which is exactly what I do
Cheers
DD
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these can get raunchy fast— …anyway, …I love driving with fresh oil and filter…kinda like new socks and undewear. So…lets talk about moly…Like LiquiMoly…big F1 sponsor…but does it do anything? my dad, a flight line engineer, thought there was moly in the aircraft engine oils…back in the B29 days…
and…for XKs that see to leak at the front and rear seals…how bout those seal sweller additives…often already IN oils touted as for high mileage cars.
Nick
I’d go even a little bit further, Doug, and say it won’t happen. If you use the oil that is specced for use in your vehicle, and keep it changed regularly, as a result of the oil – and I emphasize that – – no harm will come to the engine.
I started my first Hyundai on Royal Purple, but at oil change intervals of 5000 miles to 10,000 miles, it added up quite a bit in price difference. At about 30,000 miles, I switched back to dino squeezins, and it went 290,000 miles.
On my second Hyundai Accent, when I had the flat tappet engine apart (to repair bunged valves caused by snow in the belt) it had never had anything else but basic Walmart brand oil in it: the cam and lifters looked pristine, the inside the engine was perfectly clean. It made 220,000 miles.
Tweety made 160,000 miles, before being lightly rebuilt, and no special oil was ever used.
I’m glad I saved the money!
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In 1961, when the E-type was introduced the then current API classification was SC, that was superceded in 1967 by SD and 1971 by SE.
http://www.pqiamerica.com/apiserviceclass.htm
Surprisingly, you can still buy API SC oil, but who would want to since oil is backward compatable.
I trust your recommendation(s) without exception.
i asked the question here to get ahead of the power curve a-bit and have 12 qts on hand
Word on the street was my rebuilt racing engines achieved new life via the hands of Paul Wigton. The only oil property of interest was the viscosity, how to get it as low as the race crowd thought would be okay for getting maybe 30 races out of the engine. Thank you Wigs, running engines confidently near redline for 45 minutes at a time was a blast.
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If you really, really care about the environment.
Back in the 60’s re-refined oil was about $0.20 a quart and the quality was suspect, at least we thought it was suspect.
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Here, it used to be called Double Eagle!
The oil itself is not suspect: oil, in and of itself, it doesn’t wear out, and recycled works perfectly well as a base oil.
What does wear out and what Double Eagle did not have in it, was any additive packages. If you take recycled oil, re-add the original additive package that it came with, it’s every bit as good as brand new stuff.
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I have read various places that if one has been using conventional oil in an engine for some years it may be a bad idea to change to a synthetic oil as it often results in oil leaks. I, of course, have been using conventional oil in my older cars for years with minimal to no leaks, including the 40+ year old rope seal in my S1. Has anyone had experience changing from a conventional oil to a synthetic oil or a synthetic blend oil and either resulting or not resulting in increased oil leaks?
Tom
I long time ago, when I actually tried synthetics, I did not experience leakage or increased leakage.
FWIW
Cheers
DD
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Olestra will do that.
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Synthetic oil doesn’t expand seals the way standard oils do. But modern synthetics are supposed to include additives for the seals. That said, I’ve always found that a leaky engine will absolutely bleed on synthetics, so it depends on the quality of your seals. Try it, the worst that will happen is a little extra rust proofing.
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A oil chemist told me that the best oil is re refined because it retains hydro carbons which make it a better lubricant. 
Years ago you could buy oil that wasn’t certified so you had to check for the API stickers but I’ve not seen any in years
Personally I buy what ever is on sale in quantity at the time meeting spec ,I save more than 12 bucks and don’t think you gain anything by exceeding manufacture spec
My highest mileage car 650,000 km ( Mercedes) and I change it as recommended Ymmv
Modern oils far exceed the old specs and our jags are driven so little . Make yourselves happy 
what ever you chose , advertisers need to eat to just not on me Lol
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