Synthetic Oil V-12 XJS

[Mongiardo]

Hello everybody,

First time poster...

I have a 1990 V-12 XJS and have recently switched to synthetic oil.

Does anyone have any experience (Neg or Pos) with this switch. Also... what weight would you all recommend? I was told by my mechanic to use 20-50, so that I would minimize the loss of too much oil through the various leaks. I wish I was kidding.

Love the car though.

JM

[ 10-28-2002: Message edited by: Mongiardo ]</p>

 

[calmone]

i have never used synthetic oil, but have a 94 xjs 6 liter. my mechanic recommends 20w50 as well, and i have continually used it, changing every 3-5k. the car has 95,000 miles and runs great. good luck with the synthetic, i understand it is supposed to be better, especially at start up. i just think if one keeps up on the changes and uses the right grade it my not make any difference in the long run.

 

[Basil]

I use Mobile 1 5w50 in one of my newer cars. That's what the factory recommends, so I guess if its good enough for a 2000 car, it should be ok for an older Jag as well. But to be honest, I've never tried it in any of my older cars (like my Jag EType or Spitfire).

Welcome to the forum by the way! Glad to have you aboard!

Basil

 

[Steve]

Hello and welcome. When I worked at a motorcycle dealership the official line was always to use regular oiluntilthe engine was broken in, and then it would be safe to switch to synthetic, otherwise the engine would not wear in properly. I ran synthetic in a few vehicles, and it worked fine. One caveat however, is that if you change your oil frequently (every 2000 miles or less) you will be wasting money paying extra for the synthetic, as the regular oil is still at peak performance and does as good a job. Apparently synthetic really comes into its own when the period between oil changes is extended. Anyone else hear of that?

 

[Mongiardo]

Just to add a bit...

Since the change, the engine has become much, much smoother and the oil pressure at idle is lower. I know the first part is good, not sure about the oil pressure reactions. Now it sits around 15lb as opposed to hanging on the 25lb hash mark.

Thanks for the great tips about the viscosity, I'll try some heavier weight on the next change.

[ 10-29-2002: Message edited by: Mongiardo ]</p>

 

[RobG]

One caveat that I know is that it may soften the seals of older engines. In one old 6, and in a 12 cylinder I'm putting into a boat, the engines ran much better but decided to do their own oil changes, all over my floor and in the hull. I've also heard about this from a motorcycle wrench on older Indians and Harleys...great stuff, but you may want to put in new seals. I run synthetic engine and gear oil in the Indian, and much smoother shifting and cooler oil temps. Once the seals were replaced, the bike no longer had to mark its spot.

 

[Charles #677556]

<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by Steve:
One caveat however, is that if you change your oil frequently (every 2000 miles or less) you will be wasting money paying extra for the synthetic, as the regular oil is still at peak performance and does as good a job. Apparently synthetic really comes into its own when the period between oil changes is extended. Anyone else hear of that?<hr></blockquote>

Steve;
I've heard it.. the Syn-Oil folks "claim" their non-oil can be used for an ungodly number of miles.. and their PR Lit states the same as well..
The problem I see with leaving the "stuff" in your engine is one of the basic properties of the oil is to hold the contamanates in suspension until the next oil change.. I assume the Syn-Oil does the same.
I'm sure we have all seen engine oil so black and gritty when some "non-caring" individual only changed his oil once a year or so..
While the "chemistry" of a Syn-Oil have be such that it will handle the heat and miles, the filtering system on engines is "By-Pass" in nature.. that is, not all the oil is filtered before it is cycled back thru the engine. So, the "crud" that engines are known to produce are still being produced and spread through out the engine to do it's damage.. more-so, in my opinion, in the newer (post emissions) engines due to their higher operating temps and Leaner running conditions.
For my money, and several of my 300K mile cars, I'll stick with Dino-Oil and change it and the filter every 2500-3000 miles..
My three daily drivers are a '62 Volvo 122S, a '70 Datsun 510 (Purchased new in April '70), and a '71 Volvo P-1800 (purchased in '73).. the first two are both over 300K miles and the '71 is approching it's first 100K.

 

[aeronca65t]

Most of our LBCs don't place oil in conditions that sythetic products make a useful difference.

For something like a hard-driven Honda V-Tech, with 230 F. cooling system, 8200 RPM and 2 HP per cu.inch, it could be a diffent story.

As Charles says, the meaningful part of the problem is filtering.....standard mineral oils are much-improved in the last 40 years, but filters are essentially the same.

Regular oil/filter changes (with standard "SJ" mineral oil) is probably the most cost-effective strategy for most of us.

Additional notes on this: I'm sure most folks think that the 3000 mile (or less) oil change is a good idea....I'm not convinced....especially if you don't do your own oil changes. I've been to many service centers where the techs change the oil, spin on a new filter, and then start the engine and rev it till the oil light goes out (meanwhile, the lifters, cam followers, etc., are clanking away until the pump re-fills the filter)....If your service people follow *this* practice, you might be better off with *less* oil changes (to diminish "dry-start" wear and tear). For the record, modern automakers recommend oil changes about every 6000 miles (Porsche says 7500 miles)....I've been changing oil/filter at about 5000 miles in all my cars for years, with excellent results. As for oil brands, I buy any name brand that passes the rigerous SAE "SJ" rating (which is virtually all oils nowadays).

 

[Michael J.]

I also have a 90 XJS Convertible. I use either the Castrol 5 - 50 full synthetic ir the 20 - 50 full synthetic. As some of the other respondents suggest, the advantage of synthetic is longer intervals between oil changes. I use 6,000 miles. I did not notice an increase in leaks, but I did not notice a decrease either.

Try the product "NO LEAK", two quarts instead of one because of the 10.5 qt crankcase. I got some improvement with it.

 

[RF Thom]

Before retiring I worked as a Liaison Engineer for one of the 'Big 3'. They built the same basic engine for two differnt sports models with the up-scale model utilized synthetic, lower model petrolium based oil. The bottom line was that validation could not be otained because of piston scuffing with petrolium oil, but passed with flying colours utilizing synthetic. The 'bean counters' would not approve synthetic in the base model [cost] so cheaper option like teflon coated piston skirts were being evaluated.
Petrolium oil breaks down at 290F. An engine under load with coolant temp of 220F has an oil temp approaching 275F. Synthetic oil breaks down at 450+F, which provides much greater protection, period.
I also seen extended drain interval testing with synthetic oil where the oil was checked every 25k miles for metal presence, [iron-block, cr'shaft, aluminum-pistons, lead/copper-bearings] filter changed with top-up. Results no measurable wear at 100,000 miles and this was at wide open throttle controlling engine speed [peak torque to peak HP] with load.
I would not recommend this for your car, but 20K with a filter change at 10K is the schedule I use on my daily runners. I have better things to do than lay on my back under my daily runners every 3.5K.
As a side note to the contamintion point. Yes petrolium oil is changed for that reason of contamination, because petrolium oil will absorb moisture and it is difficult to boil it out- thus you change it. Synthetic oil does not absorb moisture so it's not even a concern here.
I also utilize synthetic coolant [long life], and synthetic brake fluid.

Regards, Bob