Hello all;

I have posted this on the other forum and here recently.

I am wanting to go over to Redline 0w40 or Mobil 1 0w40 on my 95 AJ16 XJS with 103K miles.

Right now she is running on Mobil 1 High Mileage 10w30. She leaked when I used the Mobil1 High Mileage first from the oil cooler lines and the o rings, but after I replaced those, she has been fine.

I have searched the archives extensively and I know that there are some people out there running it succesfully, I am just scared mine might be too old to go over. I would definately prefer the Redline.

 

Not my choice, but there you go.

The charts I have from various oil companies (not redline), show the following:

10W/30 74.7cst @ 40c, and 11.5cst @ 100c.
0W/40 79cst @ 40c, and 13.5cst @ 100c.

The cst in VERY simple terms is the "flow ability" of the oil at 2 specific temps. 40c is used as a "cold start temp", and 100c is the actual operating temp of engine oil.

If oil is tooooo thick it cannot flow, you got stacks of pressure, but no flow through bearings etc and they burn. The recognised cst @ 100c is somehwere in the area of 13. This is lower now due to the requirements of the "newer" generation of fuel efficient engines, such as our AJV8, that have bearing and other tolerences waaay tighter than the AJ16.

I run 10W/40 synthetic in all my Jags all year round and NO issues. I would not use the 10W/30 in any of mine, or the 0W/40 for that matter. If I ever venture to the V8 engine then my choice would be the 0W/40, due to that engines oil requirements.

Use google and find "Bob is the oil guy", and get some nibbles and alcohol and spend a night or two of very informative reading.

 

Grant thanks!!

"BOB is the oil guy" is what has me like this!!! Crazy over oil...

Hence the 0w40...easy to lubricate at start up and as thick as any 10w40 at operating temp.
I know Vee was using it..maybe he can chime in??

 

Yesterday went from Mobil 1 HM 10W40 to Mobil 1 0W40 and the V12 runs slightly cooler... Same oil pressure at 3K rpms and at idle. It also seems to be smoother and quieter at idle.

 

Here in the UK, everyone I know with an AJ16 runs 10w/40 semi-synthetic. Ow seems too thin and 30 seems too thin also. All the specialists that the club deals with also say 10w/40 semi as the best option.

Just my 2p-worth....

Paul

 

I run Mobil 1 0w40 in the winter time, when I do my fall oil change and I run Mobil 1 15w50 in the summer time, when I do my spring change.

Both are available to me in the 5 quart jugs that I can buy at Walmart for about $26/jug. Obviously I buy 2 jugs and save the remaining 1-1/2 quarts for the next year.

No leaks, no issues, no nothing. I couldn't say anything is better or worse with what I am doing.

I have read in other posts that there are people who simply run 0w40 all the time. It makes me feel better to put the 15w50 in during the hot DC summers, but I don't think it makes a big difference.

If I got lazy, I would probably go with the Mobil 1 0w40 all year round.

 

I drove my XJS(V12) this morning for 45 miles and the temp gauge stayed way below the N and never got close to it. I also let it idle for 10 minutes and the gauge never moved... I have to say Mobil 1 0W40 makes this engine run substantially cooler then it did with a heavier oil. It also is quieter at idle and runs very smooth/fantastic. Night and day over the Mobil 1 HM 10W40(a very heavy 40 weight oil) that I used in the last OCI. My oil pressure has also not changed at all... I have been a member at the "BITOG" forum for years and wished I took the advice last year and used this oil in the last oil/filter change...

 

Do we have any long-term updates on this thread?

I'm currently using Mobile 1 10W40 in my 1996 XJ12 6.0L and Castrol GTX Conventional 10W40 in my 1992 XJ6 4.0L AJ6.

I'm interested in switching to 0W40. I know our manuals suggest 10W40 for most climates, but I'm wondering if there are better choices now with today's higher-tech oils that weren't available when these cars were manufactured.

Any input?

-Nick

 

As a fellow Houstonian, I would be more worried about the second number of the oil grade the the first, definitely being in Houston and with summer coming up. We used to to run 20w50 Castrol at the dealer when I was there, never had any problems. I live in Auckland, New Zealand now, have a 94 XJ40 with the AJ6 engine, I just run Castrol Magnatec 10w40, and no problems. When I was still living there, I was using Amsoil, and have used royal purple in the past. You should be fine with 0w40. Just stay away extra additives/snake oil products.

 

I have a question regarding the shift to thinner oil (say 0W40 compared to 10W40) when the engine's head starts having worn valve stem seals.
I have an AJ6 4.0 that runs fine overall, no oil consumption but some blue smoke at start.
Wouldn't thin oil lead to increased oil consumption and worsen the wear in the head?

 

Paydase, you may notice a little more smoke on start, otherwise nothing drastic, and I doubt the wear would be any worse as both oils will hover around 13 cst at 100 degrees C.

To get back to the original post, the choice of viscosity is good, however I have read that Redline oils are high in detergents, some argue that this might cause a few leaks on older cars (old british gaskets here) however there is precious little evidence of this, so your choice. I would be most interested to hear if you do notice any new leaks if you decide to go ahead with the change to Redline, let us know!

 

0w40 is as thick as 10w40 which is as thick as 40w40...when the engine is hot.

I have done my research and have read more than I probably should have at BITOG and I now use Mobil 1 0w40-Euro Formula all year round. The only reason I would ever consider changing is to up the number to the right of the 'w'. I want the number to the left of the 'w' as low as possible. If oil weight is a concern, using 0w40 or 10w40 shouldn't be a discussion.

The oil charts for the AJ16 (TSB 12-58) seems to limit the use of 40 weight oil to 40C ambient temperatures. Dropping the 10w to 5w seems to increase the lower ambient temp limit from -20C to "unlimited". 0w can only improve upon the 5w, and until someone can explain why it wouldn't (which no one has, other than discuss the additive packs that go into oil, which exist for all oil these days), I will stick with 0w40 oil.

There is no 10w oil that is recommended when ambient temps are lower than -20C
All 5w oil seems to have no temp limit.
It shows a 0w oil, but only the 0w30, because I'm sure 0w40 didn't exist. The chart only recommends 0w30 or 5w30 oil when purely synthetic, and meets CCMC G5 specs. That seems a bit too fringey for me to consider using a w30 ever.

The Mobil 1 0w40 seems to run just fine for my AJ16. Unfortunately I don't think I can be a good source of info until something bad happens, or I can say that I've run 300k miles on the car. In this case no news, isn't useful news.

Lastly, I don't like to use High Mileage oils. I am concerned that the additives in those oils might only do harm to the engine by introducing sealers or other agents that engines don't need. If I was trying to extend an old leaky engine another 50,000 miles, yes, I would start using it, but really as a last resort, not proactively.

Hope my opinion is helpful. It really is only that, an opinion. 200k miles down the road, I'll be able to back something up.

 

You pretty much hit the nail on the head of why. 0w40s were not specified back when the cars were new because the viscosity improvers were not as good as they are today. What that means is that older oils would break down quicker causing them to thin out, so a 40 weight oil would drop to a 30 or 20 weight at operating temperature. Even 10w40 had a bad rap for doing this in the early days.

 

Almost, but not quite.

Multigrade 40 weight oils are a special case in that there are two ranges
for two categories of 40 weight oil when viscosity is measured at 100*C.

For xW40 where x is below 15, there is one range of values in cSt to
be met at 100*C, and for xW40 where x is 15 or above, there is a
higher viscosity range to be met at 100*C.

Oil is a Newtonian fluid, therefore knowing the viscosity at 40*C and 100*C,
it is possible to derive the viscosity curve for all temperatures, aside from
the effect of pour point depressants.

 

Plums,

Thanks for the insight. I stand corrected....not that it changes my position on what oil to use. I guess, if anything, it confirms that 10w40=5w40=0w40 in terms of the oil when it's hot. I stand by my position that you want that first number to be as low as you calm buy.

I'd rather get the cold startup 0w40 protection than the hot running 15w50 protection, especially since Jaguar says it's ok to run a w40 in the AJ16. As I mentioned before, I wouldn't ever consider a w30.

That's just me though.

 

Oil thread........YaY! Viscosity explanation in the link.

http://www.upmpg.com/tech_articles/motoroil_viscosity/

 

Again, not quite.

Even when restricted to below 15W, there is a range.

Then you have to define "hot" because for anything other than
exactly 40*C and 100*C, you are on the slope of the viscosity
curve.

At starting, at room temperature in say a temperate climate,
or a garage, the vicosity difference is negligible between 0W and
15W.

There is a balance to be struck between below freezing pumpability
and oil film thickness at rest.

I doubt that during the first two revolutions of the crank that there
is any useful flow at the crank bearings. Nor is there enough speed
for hydrodynamic lubrication. At this point, you are strictly operating
on boundary film lubrication.

Oil pressure is only used to supply enough oil to compensate for
the oil leaving the journal for cooling purposes. A journal bearing
can go into hydrodynamic lubrication state solely on the oil that
is already at the bearing at the critical speed, provided there is
enough oil film. The critical speed is a function of rotational
speed, journal diameter, bearing clearance and viscosity.

I suggest that a journal will reach hydrodynamic lubrication state
on fewer rotations and at a lower speed with a higher viscosity
at cranking temperature.

For normal driving, I doubt that anyone needs anything other than
a xW40 because the 100*C viscosity is just about optimal. However,
the number to watch is HTHS. That is the number that will indicate
how well your cylinder bores are being protected as well as certain
transitional conditions at the bearing. If you look at a 15W40 API
oil, you will most likely get something suitable. On the other hand,
if someone looks at a ACEA A3/B4 oil, they *will* get something
suitable.

In North America, 0W40 Castrol European sourced synthetic meets
ACEA A3/B4. It will have "Made in Belgium" on the back of the bottle.
Certain formulations of Mobil 1 and Pennzoil also meet the spec. But,
not all.

 

Been looking at the Mobil 1 0w40 for my 1997 XJR (AJ16) as well. I've been running conventional 20w50 and was initially looking at the Mobil 1 15w50, but a lot of positive information have me considering the 0w40 now.

This thread has been very helpful.

Mobil 1 0w40 has the following specs:

https://mobiloil.com/en/motor-oils/m.../mobil-1#0W-40


Specifications and approvals

Mobil 1 FS 0W-40 synthetic motor oil meets or exceeds the requirements of:
API SN, SM, SL, SJ
ACEA A3/B3, A3/B4

Mobil 1 FS 0W-40 has the following builder approvals:
MB-Approval 229.3
MB-Approval 229.5
VW 502 00/505 00
PORSCHE A40

According to ExxonMobil, Mobil 1 FS 0W-40 is of the following quality:
API CF
VW 503 01

Technical details

Viscosity, cSt (ASTM D445)
@ 40ēC
71
@ 100ēC
12.9
Viscosity Index 186
MRV at -40ēC, cP (ASTM D4684)
21,600
HTHS Viscosity, mPa•s @ 150ēC (ASTM D4683) 3.6
Total Base Number (ASTM D2896)
12.6
Sulfated Ash, wt% (ASTM D874)
1.3
Phosphorous, wt% (ASTM D4981)
0.1
Flash Point, ēC (ASTM D92)
226
Density @ 15.6ēC, g/ml (ASTM D4052)


.

 

I ran 0W40 for years in my VDP with no problems.

 

Still running Mobil 1 0W40 and no leaks... Runs smooth and as cool as it did last season. Started right up last week for the first time since November.