Seal Conditioning with Synth based oils

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May 27, 2002
Ocala, Florida
How many of you feel that syth's and some of these high milage motor oils can actually clean and condition seals in an engine like the valve stem seals for instance?

You get a chance, Give us an idea or make your argument as to why you think it does or doesn't

[ July 05, 2002, 01:29 PM: Message edited by: BOBISTHEOILGUY ]
I don't know about the high mileage oils, but I do believe that Mobil 1 keeps things nice and clean. At the same time, I also believe that it causes more leaks and more burning, mainly because it's so thin (their 5w30s and 10w30s are way on the bottom end of the 30wt scale, and the 5w30s thin out fast too)
I think Amsoil, which I use exclusively at this time (soon to try Mobil 1 SuperSyn and then Schaeffer's) has a high level of natural detergency and keeps the engine clean. Seals - never had any seal problems with either dino's or Synths. I think they all have a well balanced seal-swell formula.

Originally posted by BOBISTHEOILGUY:
patman, how does m1 do with a used engine that has been running an unknown oil? would it clean the seals and help recondition them?

That's a good question Bob! My car would've been a good candidate to check that, as I started using Mobil 1 as soon as I got it, and I know the insides of this engine were pretty dirty. I would venture to say that the answer to your question is no, because of the valvetrain noise that I had when I bought the car. I have solved it now, but it was with the one two punch of the GM lubricity additive a couple of oil changes ago, and the recent Auto-rx application. Mobil 1 alone wasn't enough to clean out my engine the way it was.

I have to say, my faith in Mobil 1 has gone down considerably in the last few months. It's not the miracle oil that so many people believe it is. Although if you tore down my wife's engine I'm sure it would be squeaky clean inside right now. (it's had nothing but Mobil 1 since new)
A problem I see is too many variables in the type of material a seal can be made out of and what ones are in which cars? It has been spoke about much here that it is more the additive package than the base oil so we all know a additive will deplete over time.Lubrizol lists 6 different synthetic bases,I expect the two mainly used in automobiles use and additive to swell the seals or to keep the seal from being attacked.What have I said here? I don't know
but I personally have chosen the safe route because time and time again all I got was contradicting information about synthetics and engine seals so I gave up!

But to your topic question yes.I believe they can swell a seal.Now is that good or bad would be the next question? It seems to me the best layed plan would be to run a mineral group II+ to 150k then swith to synthetic. Your thoughts?

[ July 05, 2002, 03:53 PM: Message edited by: dragboat ]
Oh I have some thoughts about this
but I'm still waiting to see how others think prior to my posting a new test result I just finished up today.
Cool, more test results! I love Bob's tests! Keep em coming Bob! (and don't keep us in suspense too long on this recent one either!)
I think with the modern OTC oils, both syn and dino, that they don't contain enough additive to affect the seals. The additive used concerning the seals is in the oil to try and prevent any harmful chemical reaction that would harm the seals, in effect a neutralizer. When this additive is used up, then the seals start to harden. Frequent oil changes will prevent this to a point.

To efficiently clean and make the seals pliable a separate additive is required.

Sorry if I am in left field, but it won't be my first time. Just my opinion.
Maybe a better question would be:

Have you had any seal problems and what oil are you or have you been using; and what additives have you used? Then there might be some correlation between seals and oil brands/types.
No, I'm not looking for anything more than what people are lead to believe and why they do. If belief is due to experiences then that counts as well. But my point on this topic is to either prove or disprove how synth's/high milelage oils affect seals and cleanliness as there has been many here(as well as on other boards) that state synth's or high milage oils condition seals due to the synth esters. So along the spirit of that, I deceided to see for myself. But in the meantime, lets see how others feel about this issue.
My long term auto expereriences with Mobil 1, both pre-trisynthetic formula.

My father gave me his 1984 Mazda
626 2.0 L SOHC I4 Electronic Carb and manual valve adjustment(Last year for this setup). It had been run with Castrol and changed every 3000 miles. At 100k
I switched to Mobil 1 motor oil, gear oil, and axle grease. I noticed a
1 mpg increase and 2000 miles later the cam cover began leaking. At 5000
the cam seal began and at 7500 the front main started(These same seals had been replaced at 50k). After changing
these seals, it then leaked very slightly from the pan gasket. 1
quart in 7500 and I changed it at that point anyway. Oil consumption fell to 1qt in 9000 miles, I kept changing it when it would need the quart. The valve
seals started leaking at 150k (blue puff of smoke on startup). The inside of the cam cover got very
clean(cleaner than when I got it) so it is true that the oil had a high
detergent factor (factor, NOT content.) This car was hard on its oil but the Mobil 1 looked
better at 9000 than the Castrol did at 3000. I totaled it at 175k, so I did not get to see how far the engine would go.

I then bought a 80k 1993 Olds Ciera 3.3 V6 from my mother. Non-Sequential Port Fuel Injection(Computer fires 3 injectors at a time) This was the last year for this engine, basically a destroked, debored, Series 2 3.8L OHV Buick V6 with no balance shaft and lacking the SPFI of that engine. It had been bought new and been run with Pennzoil 10W30 with 3-4000 mile intervals. Engine used about 1/2 pint of oil in 3000 miles. Switched to Mobil 1 5W30 at 80k, switched to Tri-synth at about 110k. No oil consuption change. Used 1/2 pint in 3000 and less than 1 quart in 11k. No seal leaks, no consumption changes. Inside of valve cover is still very clean at 160k. Switched back to Pennzoil in Febrary when zI gave the car to grandma. Only 2500 miles so far, but no changes to report.
I don't have too much experience tearing down engines I've run a long time but my '90 Integra saw Mobil 1 and then Castrol Syntech (when it first came out) for most of its 90,000 miles with me and at around 60,000 miles, the cam seal leaked ... but this was notorious with these cars. I can't fault any oil.

My '95 Civic used no oil for the first 100,000 miles which was almost exclusively Mobil 1 5W30. At 95,000 miles I switched Valvoline Synpower and consumption appeared ... about 1/2 quart in 5,000 miles. I switched to Red Line at around 103,000 miles and consumption (eventually) returned to zero.

No signs of any leaking whatsoever.

I think that some of the synthetic base oils have a little bit of natural detergency (esters & alkylated aromatics), but I don't believe they can revive a basket case. Also, a lot of oil burning is from rings and scored cylinders and no amount of seal swellers will correct that.
Bror Jace,
The Civic you speak of,do you know by chance what type rear main seal it uses? The type of material it is made of is whatv I am asking.
I have two vehicles which use Mobil 1. I started using Mobil 1 in my 98 ext-cab Z-71 at about 14,000 miles. My wife's 98 Grand Prix GT at about 39,000 miles. My truck currently has 40,300 miles on it and the wife's car has about 80,000 miles on it.

The truck does not leak any oil. It did have a leak at the oil cooler lines but it was fixed under warrenty.

The car started leaking oil at about 20,000 miles and even with three oil pan gaskets and one oil pan, the car still slightly leaks occasionally. The oil pan change did the most to slow it down and now it only drops a drop of oil about every 3 or 4 months. The Mobil 1 did not turn the leak into a gusher so I'm sure it has some seal swellers in it.

I used to have a 93 S-10 4x4 with the 4.3L that I bought new and used synthetic the whole time I had it and it always had a problem with the rear main seal seeping oil. It never turned to a drip but the back of the pan was always wet. The remote oil filter adapter lines also leaked but I think this was a problem with any oil that was used.

Bob I can't answer your poll because I don't agree with any one answer.

We are talking about 2 different areas here;

1. Cleaning a dirty or dried seal. Usually the normal oil flow has been disturbed causing the seal to dry out or mechanically wear or has been damaged by harsh solvents.

2. Maintaining the seal that is in use and doesn't have damage yet.

My answer is most good quality oils regardless of base oil will perform the maintenance function for a time.

UNTIL.... they run out of additive or are overheated,or oil flow is resticted,or contaminated with coolant, sand,cooked oil etc. Which is common in the real world.

Then you face the issue of a lubricant acting as a lubricant and/or cleaner /solvent. You can't do both and lubricate properly with todays bases and add packages without sacrificing one for the other.

If you start with a clean engine and it never has any events that contaminate, damage, stress, and starve the seals then a cleaning would never be needed.
Show me a daily driver that like that because they are not the norm.

Some Syn bases do clean very effectively but the adds have to counter that to provide lubricity.
DragBoat, the car is a '95 DX Coupe with a 1.5 liter engine ... 102hp stock.

That's about all I know. I have never had to have any kind of repair on this motor save a rotted out exhaust system.
I have used Amsoil synthetics for about 11 years with about 7-8 different cars. My experience is that if switched to synthetics early on when new the oil seepages and leaks will not begin to occur until after 100,000 miles. If the car was purchased used anywhere after 30,000 miles (a few of the 8 have been ) my experience has been that seepages begin to occur within one year of the switchover. Not heavy leaks etc, just seepages that are not worth getting repaired.

For whatever reasons synthetics do have a tendency to seep oil.
I find that interesting as I have never used a full synth but for the last 8yrs now,I have never experienced any leaks after a change over to the schaeffers blend.

I have heard of many that have experienced this problem with seals leaking after a change over to full synth's. It's possible that the reason for not having a problem is because of the procedure of using our 131 prior to change over, where it cleans and conditions seals. Of course I cannot say for a fact that this is the case but it sure hasn't hurt.
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