Read some archives but didn't see this question asked: is there a potential gasket issue associated with a change from conventional to synthetic engine oil? The reason I ask is that at 50K miles on my 01, I had the tensioners replaced. The shop commented that the engine was super clean. He showed me my tensioners and some that had come off a car with $70K miles. Mine were perfect and clean. The others were dark, stained and messy. He asked if I used synthetic oil. I told him I had asked for standard oil the last change because I did not know what had been used before I purchased it.

So, the deal is that, for marine engines, from all the years I have been involved, the recommendation is to stick with standard oil rather than switch to synthetic after the engines have any material hours on them. The rational is that the gaskets will shrink and leakage will ensue. Further, the synthetic acts like a solvent and will require some short frequency changes due to deposits it will loosen up. This based upon marine tech's recommendations.

Any comments? I am frozen in fear that a dry engine would start weeping...

 

I've heard that they condition the gaskets differently. I've changed all my cars to syth. as it suits my driving habits better. That said I run syth in a 29 year old TVR with a very much old school 2.8l ford iron engine. Did it leak after changing fluid? Sure it did, I would even say it leaked a bit more than normal. 3 months later the leakage is back to normal for a British car. Might use a quart including leakage over a year or about 3k.

 

Use whatever you're most comfortable with. There's probably no topic that causes greater and more frequent unresolved debates than oil, filters and additives.

 

Yes, on the sailing forums, this has been beaten to death. Of course, marine engines tend to be run at 70-80% for many hours at a constant RPM in a clean environment, but also are very often older engines. So, the operating environment is far different. I wish I had done an oil analysis before I had the oil changed on the XJ8, but that's in the past. I have a similar issue with my 06 Subaru in that it is a turbo and works hard going up my mountain; with 135K miles on regular oil, I do not have the nerve to experiment with synthetic. I notice Mobil 1 is a site sponsor. Just for grins, I may check their Q&A's or send a note. Regardless, I'm timid on this. (PS: I use Baldwin filters exclusively )

 

Hi Rick,

The way I recall reports I heard maybe 15 years ago was that changing to synthetic oil was usually not a problem, but that going back to conventional oil afterward could lead to problems. The theory was that synthetic oils caused seals to swell, and if you switched back to conventional oil the seals would shrink again and potentially lead to new leaks. I don't recall ever reading a definitive study that proved this to be the case.

In my own experience, running synthetic oils in our '88 and '93 didn't seem to cause any increase in oil leakage. However, running synthetic oils with a lower base oil (cold) viscosity than the Jaguar spec, for example, Castrol Edge 0W-40 instead of Castrol GTX 10W-40, did seem to lead to increased oil leakage.

This topic always produces a lot of contradictory information and opinions, so I'll look forward to reading future responses!

Cheers,

Don

 

Not sure what to make of this:
MYTH: Mobil 1 synthetic oils will leak out of the seals of older cars.
REALITY: Mobil 1 oils do not cause leaks. In fact, new Mobil 1 synthetic motor oil was tested in dozens of industry standard and original equipment manufacturers (OEMs) tests to prove its seal performance. It is fully compatible with the elastomeric materials from which all automotive seals and gaskets are made. If an older engine is in good condition and does not have oil leaks, Mobil 1 oils provide the same advantages as when used in a new engine. ExxonMobil recommends taking measures to repair the leaks, then using a Mobil 1 oil. ExxonMobil also recommends following the automobile manufacturer's manual for the proper oil to use.

 

Rick-

Given that there's no real advantage in switching to synthetic other than potentially a longer change interval that very few take advantage of, and the interweeb rumours have got you nervous, why bother?

 

Mobil1 used here since I bought "Her Majesty" at 99k miles (no clue if conventional or synth. used up to then). 121k miles today without any issue (changed 3 times in that interval though).

Cheers

 

Reportedly, the advantages of synthetic oil go beyond longer change intervals and include reduced internal friction and heat due to a more uniform molecule size. Here's one reference that doesn't appear to be tied to an oil company:

HowStuffWorks "Synthetic Oil Pros and Cons"

And here's one that is more detailed but may be less objective:

http://www.autoguide.com/auto-news/2...r-vehicle.html


I don't know about the X- or S-type, but for our X350 Jaguar specifies synthetic oil only (as does BMW for our '04 325i). I haven't studied the reasons, but I assume they have to do with engines designed to take advantage of the specific properties of synthetic oil, resulting in reduced power loss to friction and heat and improved performance and fuel economy. I haven't studied whether an older engine can benefit from these properties, but I'm anxious to hear from anyone who has.

Cheers,

Don

 

Don-

I was first exposed to synthetic oils in the late 70s in my professional life and became intrigued by the potentials mentioned above. In the intervening years, I've never found real evidence of said things making any difference in the real world. Engines outlast the rest of the car in the vast majority of cases irrespective of what type of oil is used.


The 2004 X350 manual makes no mention of synthetic oil at all. Can't say for BMW.

 

Hi Mikey,

True, the X350 manual doesn't use the word synthetic, but it does specify oil that meets the (Ford) WSS-M2C913-B specification, and most of the oils I've found that meet that spec are either fully synthetic or synthetic blends (Castrol GTX claims to meet the -B spec, but Pennzoil's conventional oil only claims to meet the earlier -A spec). -B was superceded by WSS-M2C913-C and Ford now strongly recommends its use in all applications where -B was originally specified. Based on my limited research all the oils that meet the -C spec are fully synthetic.

The X350 Vehicle Maintenance Checklist recommends oil changes every 10,000 miles, which seems longish for conventional mineral oils.

I found this interesting TSB about oils for the S-type that states that V8 vehicles for the Mexico market must use fully-synthetic oils, apparently due to the high ambient temperatures:

http://www.jagrepair.com/images/TSB/...gine%20Oil.pdf

The parts manager at our local Jag dealer told me that they use Castrol fully synthetic that comes in large drums. He mentioned a name but I couldn't recall what it was, but a google search brings up Magnatec, which may be what the name he mentioned:

MAGNATEC | Castrol Oil Products | Castrol MAGNATEC

(I know you're aware of Castrol/BP's marketing relationships with Jaguar, BMW and others, so we don't have to get into all of that! )

Cheers,

Don

 

Actually, no. Here's what the manual for your year of car says:

"Oil specification: API SJ/EC and ILSAC GF-3 Oil"

followed by the usual list of viscosities for different climates. That's it.

The spec you quoted is for later (2008+) cars


Not really. There's many vehicles today using conventional oils with a 15K change interval. 10K is considered old school 'conservative' these days.


There are situations and vehicles that can derive benefit from synthetics and/or higher viscosity oils but my/your cars and climates don't meet those criteria. You'll note that the bulletin also requires 5W-50, 15W40, 15W50, 10W40, or 15W-50 which are not permitted elsewhere.

It will do no harm in using synthetic of the correct spec and viscosity, but there's a big difference between that and thinking it will result in something tangible. Each to his own.

 

The seal thing is, I think a hangover from the very early days of synthetics.

Anyways, I use conventional or synthetic interchangably in the engine depending on the viscosity range I want.

Rotella 15W40 is only available as a conventional and has served many truckers well. So, conventional it is. It's also cheap as chips.

Rotella 0W40 is only available as a synthetic. So, synthetic it is.

Having noticed no discernible difference between the two in cold cranking after two day soaks as low as -35*F, and liking the warm weather behavior of the 15W40 better ... it's back to 15W40 next time. No problem, I used to do the -35*F starts with 20W50 Castrol GTX which was my former poison of choice. If you bite your tongue just right, stroke the dash, pump it just the right number of times 7.5L of Poncho V8 will fire right up after about three groans

The engine leaks not a drop on either. Nor does it require any makeup oil in between drains. From initial fill to change, the oil is always where it was the last time.

The oil is always checked after a full night rest in the garage.

 

Minus 35 deg F.

I'm so pleased you did that particular piece of research for me! I'll stick with our

Graham

 

An engine that leaks will often leak a bit more with the synthetic. Conventional oils become thicker as they cool and gaps in seals larger as the engine cools -- so the cold conventional oil does not leak out. Synthetic oil is thin when cold - so will drip a bit more.

One of the XJ's had a wet spot on the real valve cover after switching.

Both of my Nissans will drip a bit with synthetics -- just a bit wet with conventional. I use conventional or high mile semi in them -- hate drips on the driveway.

 

Just checked and the pdf manual I've been using is dated 2007 so it probably does apply to the '08 model year. Since our engine is supercharged and I enjoy it as often as possible, I'm happy to spend the extra money on fully synthetic oil. As you state so well, "To each his own."

Cheers,

Don