Well Mikey, we finally agree on at least one thing:

If there was a clear advantage to synthetics the OEM would recommend it and use it.

Synthetic's main advantage is to extend the change interval, which takes us full circle 10 posts ago. So, no big deal.

 

Several OEM do, in fact, install and require synthetic, guys - Mini Cooper, for one.....

 

Yes, agreed. My BMW "requires" synthetic oil changes, (typical BMW). BMW also provides free maintenance items such as oil changes.

I believe they are vastly more likely to get bulk purchase pricing perks from the oil suppliers given the higher production numbers and visibility BMW gets with a far better warranty cost model than Jaguar has ....I don't understand it, but I think it is true.

 

Yes, there are cars that specify this. Anybody know how they substantiate it from a technical pint of view?

 

Sorry, I keep hitting send too soon.

The other point about BMW, they are moving to a 15K change interval which is consistent with one of the primary benefits of synthetics, extended change intervals.

 

I am contemplating using Royal Purple for the Jaguar. Anyone used this before?

 

I know some who use RP in their Jags. No problem with it. I don't use it myself, but it's simply a personal choice and local purchase convenience. I'm using Castrol syntec 5W30 in my Jaguars and BMW. I've also used Mobil 1. I know people who use Pennzoil Platinum, which I don't like based on an independent study I saw that ranked it at the bottom in a field of synthetics. Even then, it's not going to kill anything.

 

Dino oil and synthetics differ in that the molecules that make up the oil are all identical in size with synthetics. Think of it as cloning. Due to this consitency at the molecular level, sythetics can withstand heat and pressure better, thus retaining their viscosity much longer. This is where you get "sludge" build up with conventional oil. As the oil breaks down, the molecules begin sticking together. I've read reports from independent lab tests and have chosen to typically use Mobile 1. Amsoil rates slightly above, but not enough to justify the additional cost. Royal Purple also ranks pretty high. Castrol Syntec is actually a blended oil. There are no laws dictating what oil companies can list as synthetic, but usually if it reads fully synthetic on the bottle, it's a safe bet. Just my $0.02 on it.

 

There are two Castrol Syntec products - Castrol Syntec and Castrol Syntec Blend. I use Castrol Syntec or Mobil 1.

http://www.castrol.com/castrol/produ...tentId=6030793

http://www.castrol.com/castrol/produ...tentId=6030819

 

Oils that previously were not considered as synthetic, such as those that are produced by severe refining, hydrogenation or other complex chemical processes that yield a more stable molecular uniformity and higher degree of purity that is not achievable through normal conventional refining process are now also labeled as synthetic by their respective producers (SHELL, ExxonMobil, BP, SUNOCO) - they however still are made from petroleum crude. All synthetics have additive packages that are carried in the synthetic or so-called synthetic base by a carrier of regular old crude.

Castrol Syntec Synthetic Motor Oil, which when first introduced and up until December 1997 was formulated with PAO (Poly-alpha-olefin) sourced from Mobil.
In January 1998 Castrol started to use much cheaper hydro-processed petroleum base oils from SHELL. Mobil lost the opportunity to sell PAO to Castrol. Mobil Oil complained to the National Advertising Division of the Council of Better Business Bureaus, which in April 1999 finally ruled in favor of Castrol, specifically allowing Syntec Motor Oil made from Shell XHVI slack wax stream to be sold and promoted as "synthetic".

 

Hi,

I am not sure I understand the meaning of your post above. It appears to be a cut/paste. I am not a chemist or a petroleum engineer, but only a consumer using a product that happens to be Jaguar's recommended oil supplier.

Are you suggesting using Castrol would have some detrimental affect? Just trying to gain a little better understanding of your reply.

Best,

 

Yeah, it is a cut and paste. Just some information that I came across regarding synthetic oils. They are not all created equal, and what you get is not always what you may think. I've use Castrol myself with no ill results, but I also used to think that it was a pure synthetic. In my opinion, Castrol makes great oil, but I just figure that if I'm going to pay extra for something, then I want what I'm paying extra for. Basically, each manufacturer of oil can determine what they are calling synthetic, so there's a lot of different variations out there. Car manufacturers will recommend whatever they are getting paid to recommend as long as it meets minimum requirements developed by their engineers. Also, and especially so if they happen to sponsor some racing endeavor for that car manufacturer.

 

Different oils have many diferent characteristics. Some oils adhere to metal engine components better than others, providing better lubrication. Some break down more quickly when heated under more strenuos working conditions. Non-synthetic is more viscous (thicker) when cool and thins when heated. Synthetic remains more consistent. Pour oil from both a bottle of syn and say 10-30 non-syn and see the difference. I prefer syn, but as it is consistently a thinner oil, I think it is more apt to squeek past seals and gaskets. I have replaced spark plug tube seals and a rear seal on a 2003 S-Type (4.2L V8) at about 4,000 km after warranty ran out. I would think that the non-syn oils are breaking down in the higher temperature Mexican climate, so they recommend the syn to overcome this problem.

 

Hi. I have a 1999 XJ8.
I had noticed that someone mentioned a 15k oil change interval, so I was wondering if RP, Castrol, Mobil1, etc. have a stated oil change interval. The only one I am familiar with is AMSOIL. Their stated oil change interval(s) are 25k miles and 35k miles (or 1 year).
I have, for years, followed the 25k mile change (with oil filter change every 12.5k), and had the following results:
1. 1995 Honda Civic - 4 cyl., manual trans. 307k miles before selling it. (42 mpg if you believe the odometer)
2. 1996 Ford F150 - 5.0 liter, auto trans. 286k miles before selling it (16 mpg).
3. 1996 Ford F350 - 7.3 Powerstroke, auto trans., 387k miles - still have it (18-19 mpg).
4. 1999 Oldsmobile Aurora - 4.0 liter V-8, auto trans., 240k miles - still have it (30.1 mpg).
5. 1977 Suzuki GS750 motorcycle - 78k miles before selling it (don't remember mpg) - this is the first vehicle I started using AMSOIL in.
6. 1979 Suzuki GS850 motorcycle - 86k miles before it being stolen (45 mpg).
(all mpg above were highway average calculations)

Thus, it is my experience that if I used dino oil, the cost would be quite a bit higher than AMSOIL (with the 4 oil changes per year vs. 1, or 6 changes vs. 1 at 25k miles per year), though it is initially quite a bit more expensive.

In my business, I stack up the miles per year very quickly, so it may not be as economical to someone who only pulls their car out once in a while, though dino oils recommend oil change every 3 months - so AMSOIL still is more economical than dino, I think. But then, I am a preferred customer, so I don't pay quite retail for it.

But, for all this, I was just wondering about the recommended oil change intervals of the other synthetic oils.

 

ysgeye

There is nothing like the voice of experience. I personally am not familiar with AMSOIL, as I have not seen it regularly available in the Calgary area. May I respectfully ask if you have a vested interest in AMSOIL? If you use it exclusively, you may not be able to judge if you are experiencing a greater occurence of engine gasket & seal leaks, but never the less, do you think you are? Also, I find these recommended oil change intervals as you guoted "Their stated oil change interval(s) are 25k miles and 35k miles (or 1 year)." staggering, in a good way and I intend to research this further.

Best regards

 

Thep: I tried to be an AMSOIL dealer at one time, but I think their "legal" department is run by incompetents (my humble opinion, of course), so no, I don't have any vested interest in the company.
I do have one vehicle that I don't run AMSOIL in and that is my 1985 Corvette. I think I have put MAYBE 5000 miles on it since I got it 15 years ago, so I am using the dino oil in it (I am a bit of a tightwad and don't think paying the AMSOIL prices is worth it for a car that mainly sits for long periods of time - and no, I don't change the oil every 3 months since it is practically "new" oil by the time I get it on the road anyway. When I actually do travel in it for extended periods of time, I do use the 3 months interval, though, because, one never knows when it will be sitting for long periods of time again.)
As for leaks, the Aurora has a small leak, but I think that can be rectified with a bit of tightening the oil pan bolts a bit. The Corvette also has a small oil leak and I think that is because the oil pan gasket is as ancient as the car. Neither of the leaks are serious - probably less than 10 drops per week if that much.
By the way, I would caution anybody that if you are going to use the AMSOIL transmission fluid, if you haven't changed the transmission fluid in an overly long period of time/miles, you may want to not use it since it has the effect that it cleans out varnishes and what not and the three times I have done that, I developed problems with the transmission in a relatively short period of time- the cleaning causes leaks that were prevented by the old varnished trans. fluid and other things. It might just be coincidence, but I have been told by mechanics that if you are way off on transmission fluid change time, you might as well never change it since any new transmission fluid is a cleaner and would seem to have the same affect in causing problems. (Which makes me wonder about the "sealed for a lifetime" - or umpteen years - transmissions Jaguars put in these cars.)

 

My Jag mechanic, who is a Jag specialist/restoration shop, recommends synthetic blend. They claim that that yo can't use full synthetic in Jag engine as it will damage some O rings that are made out of rubber. The full synthetic oil turns these O rings into a hard shell. I am not really familiar about all these details, but considering that they have 50 years experience or so and is a Jag independent specialist I would never put full synthetic in my engine.

 

If you drive your car wether it be a Daihatsu or a Jaguar regularly and change the oil at 3,000mi intervals you can use conventianal or synthetic oil. The synthetic will last longer because of its chemical makeup, but do you want to run the same oil for 15k without changing the filter? 15k oil change is a selling point not good maintenance The synthetic will also take longer to drain into the oil pan if the car sits for a long time, that way you dont dry start the engine. It takes conventional oil about 6-8 months of not running the engine to drain to the point where its not lubricating engine components.

In conclusion it all has to pass SAE standards to be sold on the shelf of any U.S. store. If you change your oil in 3,000mi intervals any oil will be ok.