My Jaguar has just over 111K miles. For the past 12K miles I had been running Rotella 15W40 synthetic. The Rotella seemed to make the car run smoother, however, at cold startup this summer I was getting a dry sound from the timing chain. My mechanic friend, who specializes in restoring older Jaguars, told me to get 20W50.

A few days later UPS brings me 9 quarts of Amsoil 20W50 and after install
W O W. Big difference. So much smoother and better driving enjoyment (less vibration) and no cold startup issue.

Just a heads up for anyone in warmer weather dealing with a similar issue.

 

Yep, the "old timer" mechanic at Jaguar of Cary, NC told me to run 20W50 year round.

He's the tech that exclusively does service of the "old" Jags at the dealership. He says that Jaguar always spec'd 20W50 in the straight 6 engines until increasing pressure for fuel economy had them specifying lower weights in the AJ16. And then problems like tensioners leaking down started showing up.

20W50 is all they use/recommend on our models.

So far no more tensioner rattles since I've switched.

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I recommend/use Castrol 20W50 from Walmart (cheaper in 5 quart jugs) in all the AJ6/AJ16 engines here in Texas.

Other climates might use different viscosity.

bob gauff

 

+2 on Bob's and Al's recommendations. The Owner's Manual for our '93 XJ40 specifies 20W-50 except in extreme cold temps.

And +1 on Bob's recommendation of Castrol in the 5-quart jugs from Walmart. Whether you run conventional or synthetic, it's the cheapest way to buy oil in DIY quantities.

Cheers,

Don

 

I use Castrol 20-50 all year round and it doesn't seem to be a problem even when its 0. Also, I was told not to change to synthetic since the car came with "real" oil. It would be easier for me since my other car uses Synthetic.

 

When I first obtained mine, I switched from whatever it had to Valvoline 10w-30 synthetic. Had to put in 2 or 3 (maybe 4?) quarts of make-up oil to make it to 5k miles on that change. Switched to Valvoline's 20W-50 Racing oil for whatever additives the racing oil has more of that the enviro-weenies have caused to be extracted from regular oils (phosphates?) but...that change was in late fall and winter came. Although we didn't have many of them...we had several mornings where the temp was an uncharacteristic 20's F or even in the teens. Lots of clapping and tapping and cacaphonous noise for quite a few minutes on those start-ups.

Next change was to the 5W-40 synthetic (Shell T-6) that I've been using in my Excursion for a coon's age. It has been perfect.....doesn't run through the AJ-16 like guano-thru-a-goose the way the 10-30 did, no noise on start-up...anytime...fast cranking on cold-winter-mornings....and I've commonized within the past year and started using it in both S-types and both F-150's as well!

This summer I converted the John Deere, LX-277 AWS to T-6 usage and the last and final vehicle to changeover will be the 1970's era Massey-Ferguson 1010 3-cyl diesel tractor..whenever I get 'round to changing oil in it.

Dagny, fwiw, I believe ALL of those vehicles left the factory equipped with "real" oil and the only problem I experienced was with the John Deere - Kawasaki 17HP twin - Massive oil leak at the sump gasket overnight the very evening I changed the oil. In fairness, I hadn't been very diligent in oil changes on that one in the past..and partly due to that, ran a "snootful" of ATF (A Brutal trick) in with the old oil for 15-30 mins before I changed it. Could be coincidental - the interweb is rife with stories of Kawasaki engines running the crankcase as a vacuum rather than positive pressure and everyone claims at 8-10 yrs it sucks a bit of the sump gasket in and starts leaking..."Change it and you'll have another 10 years of trouble-free service." And I bought this one new...15 years ago..so I was due....yes...there was a 3/8" long bit of sump gasket floating freely around the sump when I got it disassembled to replace the gasket.

 

Each to his own I guess, but I do wonder about the longer term wisdom of using a "thicker" oil than specified by Jaguar. I don't doubt that it will improve/ cure the tensioner rattle on startup issue, but at what cost?
It is no coincidence that manufacturers now tend to specify thinner oils, but also supply vehicles with six digit odometers. A momentary glance at any used car website will reveal large numbers of vehicles with mileages north of 100k, with engines that seem to have plenty of life left in them, and which haven't had any major work undertaken.
It is also worth noting the various manufacturer specific oils on sale. Even allowing a healthy dose of cynicism, there must be something in all these viscosity numbers which is important.
My upper tensioner rattles too, and it annoys me. Not enough though to sacrifice the correct , thin, grade of oil which will find its way round the engine quickly on startup, when most wear occurs.
As an aside, I read a thread on here suggesting putting spacers behind the spring on the tensioner, which seems to produce the desired result, and is on my to do list.

 

Don't disagree regarding shade-tree mechanics somehow having more wisdom than the engineers that designed the cars and the risks following that path entails.....

But in this case 20W-50 is spec'd in the owners manual as one of the recommended weights. So I think all is well in using that weight.

.

 

As Al commented it's an option in the owners manual. In the '80s, VW recommended 20w50 in GTI's and even Road & Track asked one of the head engineers about it and he confirmed that, for VWs at least, the heavier oils *in the warmer climates* were better for the engines. (I had an 85 GTi and ran 20w50 from April to October. Arkansas routinely has weeks of 100+ temps over the summer, like much of the southern US)

Most manufactures have several oil weights that they recommend based on average ambient temperature. I know most of my vehicles run slightly cooler with a heavier oil in the summer and I've never had a problem with overheating using a heavy oil. I HAVE had a problems running light oils in the summer (5w30) in some vehicles, even if they've called for them.

If I lived in Scotland, I'd probably share your concern because you probably are more at risk from low winter temps than summer highs if I'm not mistaken.

For any vehicle, ambient temps should factor in to oil selection. Even if using synthetics. All the mechanics and even the car dealers I've talked to agree that the push for lighter oils is more about raising the MPG and not about making the engines go 250k miles.

YMMV

 

I specifically asked the "old timer" mechanic here in NC if I could/should run 20W50 year round, and emphasized "even in the Winter" (in North Carolina, where we can get into the teens/20s F) and he said yes I *should* use the 20W50 year round and it is fine in our NC Winter.

But YMMV as noted above based on your regional year round temps.

The manual states different weights based on your regional temperature ranges.

What I'd recommend is inquiring with some local highly regarded Jaguar mechanics in your region and see what they recommend.

.

 

Al,
The manual does indeed include 20w 50 grade oil, but only for the hottest climates (90-100F). This would comfortably exclude Scotland, but also the vast majority of the US for the vast majority of the year.
With the greatest respect to veteran Jaguar mechanics, ( who's advice I generally value) this is an area for which they are very poorly equipped to comment. The factory would have been perfectly happy to recommend 20w 50 all round if it was the best lubricant all round.
The body of evidence across all manufacturers is that oils need to be thinner, and I contend that 20w 50 is too thick for the AJ16 in temperate climates.
As I said at the outset though, each to his own. I don't think that your engine will be at any risk of seizure or failure anytime soon, and given the longevity of these engines, we may simply be debating how to make an engine last 450000miles rather than 440000. A subject I suspect neither of us should be losing much sleep over!!
With best regards

 

countyjag-
In general, I agree with you, especially about advice from mechanics, with one exception. Remember that the factory recommendations are for new engines. The majority of X-300s now in service have quite a few miles on them. I will say that running 20 w 50 in my old (>200,000 miles) X300 lowered the oil consumption to less that 1 qt per 7500 miles or so. I assume it is better for the engine performance to not be "burning" oil.

BTW, the specific advice from the Jag mechanic above is, like most all of his advice, spot on, since he said "here in Texas", where the temperatures are as you quoted.

 

You've said a lot in this one statement. It is true, but only insofar as the manufacturer's goals and objectives align with an owner's goals and objectives. So I think a more precise way to put it is they are happy to recommend the best all around lubricant to meet their corporate objectives.


If you are the sort of person who trades in your 2 or 3 year old car on the new model every 2 or 3 years, you can rest easy that the manufacturer's goals for their product's longevity, reliability, and performance are reasonably congruent to your own.


The realities of the market are that a miss on corporate average fuel economy costs much $$$; as does an engine that struggles to survive the warranty period. (V8 timing chain tensioners, anyone?) So if I offer a warranty of 36k, 60k, or even 100k miles and an oil spec change offers a 10% increase in fuel economy but decreases engine life by 33%....I may ask, where do our engines nominally wear out? 300k. Fine, go for the fuel economy, engines will still last 2x our greatest warranty exposure.
Furthermore, don't discount costs out-of-hand. If a manufacturer can obtain 10w-30 in bulk for $0.10 less/liter than 0w-20, and engineering says no appreciable difference in performance/reliability; guess what the manufacturer will use? And they will specify what they use. If I'm making cars that take 9L to fill and I plan to make a half-million of them per year... and I can save a dime/L? That's $450k directly to the bottom-line. That will get a purchasing agent and/or his/her immediate supervisor handsome promotions.


My point is what is best from the manufacturer's perspective is not always best from the 3rd owner's point of view..... though in general it is always a "safe" option.

 

Here a copy of the owner's manual oil viscosity chart.

If you're using conventional oil, anything from 15w40 to 20w50 is recommended between 0°C to more than 40°. Sounds like Arizona, or Australia!

But 5w40 is recommended for anything below 40°C, included lower than -30°C. Sounds like home! But the point is that 5w40 is a synthetic range. Conventional oils cannot bridge that wide of a viscosity difference.

My XJR came from Florida with no maintenance records, so I assume it lived on something rather thick. When I bought it I flushed the engine with Amsoil Engine and Transmission flush and have been using Amsoil AMO 10w40 oil year round. Our climate varies from -30°C to +30°C and I do drive my XJR is the winter at times, so if I only looked at this viscosity chart, my oil choice would be too thick for our winters as 10w40 is only recommended down to -20°C. Yet Amsoil AMO is fully synthetic so it has a far lower pour point than a 10w40 conventional oil, -44°C in this case.

This Amsoil 10w40 meets SL/CI-4+ specs, so it has the higher zinc concentration of the older gasoline spec and it's diesel rated so I could actually use it my 2006 Dodge Ram Cummins turbodiesel. The point I'm making is that oil viscosity is only one parameter to think about when choosing oil. I don't believe everyone should be as fastidious as the guys on the BITOG site, but there's a big difference between conventional and fully synthetic oil in operating temperature range. Contamination of oil is less of an issue for our engines because of the large sump capacity.

Using a thicker viscosity than we might think based on experience with other marques is a good thing, at least if using conventional oil. But a thinner synthetic oil will achieve full oil pressure and therefore lubricate faster at startup in all temperatures, and will break down less at high temps.

If I was using conventional oil I'd probably do spring and fall oil changes and use 5w30 winter and 15w40 summer. If I had a naturally aspirated 4.0 and used it in winter I'd use a synthetic 5w40. But for my XJR that I do use as intended in the summer and used in our winters, it's synthetic 10w40 for me.

 

Jaguar manual says 10w/30 in winter, and 20w/50 for summer.

 

Jaguar manual says 10w/30 in winter, and 20w/50 for summer.

 

Yourr car is well beyond the worry of plastic tensioners.
The upgrade was sometime in 2002 to the final metal ones.

 

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