Oil Change Viscosity
 

Just need a Second Opinion please Guys.

I am going to do an Oil Change on 'The Ice Princess' XJS V12

For which I am planning to use Fully Synthetic TQX

Any advice on the Viscosity I should Choose?

I was thinking 10/40 or 15/40

This will be another "War and Peace thread, just wait.

I run Castrol Magnetec 10W/40 in all the HE engines, and 20W/50 in the PreHE, of whatever is on special on that day.

The engines are early 1960's design and clearences etc, are based around that era, and 20W/50 was the oil of flavour back then, if your market was so blessed, ours was NOT.

We had SAE?? and that was it, until the very late '60's, when some multi-grades appeared.

You dont get our stinking hot summers, so 15W40 would be MY choice. As for Synthetic, weeeeeeell, that is your decision alone. The engine does not really need it, the owner may have the "warm and fuzzies" coz he/she has Synthetic in it, but without VVT, and other items that commanded very fine oil gallery drillings, the engine really could not care less. As long as the 10ltrs is good quality, and changed when needed the V12 is happy.

Cheers Grant

15W40 it is then!

Now back to building 'The Wizard' a Shrine! :icon_imnotworthy:

depends on the weather, my HE likes 10w40 and 20w50. I usually use 10 or 15w40 because the land rover uses it too. In the winter it definitely runs better on 0w40

I have used Castrol 20W50, Mobil 1 HM 10W40 and now Mobil 1 0W40... My car just seems to run smoother, quieter and cooler on the 0W40. I am very picky about all the cars I have and can tell when an engine runs better on a certain oil. No leaks either. LOL.

Hi Sidescrollin

I've just got to go with the British Climate, so what Grant has advised makes sense.

Hi John

I am going to go with what Grant has advised, as it will suit the Climate in the UK.

I topped mine up the other day with a 1 litre 10W40 as advised originally by the Great Wizard. (First time since buying it :) )

I'm doing my oil change next time I'm home so interesting to see how you go.

:icon_bump1:

We will have to compare notes, as I will be doing an Oil Change on 'The Ice Princess' as soon as I get her through the MOT.:icon_drool:

It gets very warm here in Wisconsin with 90 degree plus temperatures and Mobil 1 0W40 seemed to perform very well. I'm sure just about any decent 40 weight oil should be fine.

Yes you are probably right but I'm sticking with 'The Wizards' recommendations.

You may already know this, but a 40 weight oil rating is at operating temperature. The first number if it is a 0, 5 or 10 is the weight at startup... All my years owning muscle/classic cars has made me want an oil that can protect quicker at startup. I'm sure a 5w or even the 10W multi-weight oil will work just as fine. Enjoy.

Didnt know this myself. So how does it work? This is talking about viscocity right? An oil that can protect quicker at startup would have a lighter weight or heavier weight? Does this also vary the price of the oil?

Paul,

The first number is the COLD temp, or as per the spec charts of oil companies is @ 40c.

The higher number is the ACTUAL operating temp vicosity, and is deemed to be @ 100c.

As the years have moved on, so has oil technology. Not that long ago nearly all you could buy was 20W50, and sometimes a 15W40, and mainly Mineral oils.

OK, Synthetics were out there, and had a niche market following, but the general motoring public ran with the 2 popular spec oils.

Then engine makers starting fitting VVT, and all sorts of intricate innards to get more oomph out of the smaller engines, so some very small oil gallery sizes appeared, and Mineral oil sludge was a mandatory NO NO, and that is where the Synthtics stood up.

The prices of Synthetics has dropped significantly of late as more and more vehicles call for this type of oil as STANDARD.

The comment on the "40 weight" oil is SPOT ON, and the lower number can be played with by you to suit your particular engine, as NO 2 engines are exactly the same.

When the time comes to dissmantle the V12, and you get to the oil pump, this discussion becomes a none event. That V12 oil pump is an AWESOME piece of engineering. It flows HEAPS of oil at a HUGE pressure, and that is why the V12 is so strong. Its design is almost identical to the pump in your auto transmission.

Hi Grant

I never knew any of that!

Would there be any advantage of using 0/40 to protect on Start Up over 15/40?

In my opinion, not in a V12.

My V6 S Types call for that spec, and neither engine is all that sweet on it. The Black runs 10W40 Synthetic, and the Silver runs 5W30 Synthetic. They have approx 110K kms on each, and were purchased s/hand, so who knows what happened before me.

Give it a try, it wont kill it.

The V12 is such a low stressed engine at idle, and to about 2000RPM, (it bever really gets stressed anyhow), the arrival of oil 1 or 2 seconds after the fire in he belly begins is of little consequence to me. Then add the fact most V12's kind of "wind up" to start, the oil is there. The odd ones that fire on the first rotation (my bloody V12's) are stiil just fine.

There is a website for those that are interested: bobistheoilguy,com and I find a lot of the stuff very interesting. Put aside many hours of reading, Paul will be fine for this, he has time to burn HAHA. I am NOT connected in any way, just before someone jumps on something, duh.

Cheers Grant

I'm laid up with the Flu at the Mo, so can't get on with installing the ABS, so I've got plenty of time for a read!

Which reminds me to Call up 'Room Service' aka the GF for yet another Cup of Tea but may have to resort to a drop of JD if my situation doesn't improve.

I have been a forum member on bobistheoilguy.com for many years and that is why I started using Mobil 1 0W40 in a few of my cars. It is a very highly thought of oil on that sight and it is very affordable here in the States. If you want a 40 weight synthetic oil, Mobil 1 0W40 is about as good as it gets.

That is interesting! but if its so good I'm wondering why they bother to sell Oils of other Viscosity, apart from OW40?

So... I think I understand this better now (thanks)

An oil that is 0W40 has Zero viscosity at startup (is that possible?) and hence can lubricate your engine quicker that say a 10weight?

Once we are up to normal running temp the viscosity for all the ones mentioned is 40 and are the same yes?

So in theory a 0 weight oil would be the more expensive oil to buy right, as it delivers faster on start up?