Synthetic hunts leaks?

[mjoekingz28]

I had four jugs of synpower left from my previous ride and thought I would put it in my next vehicle. I then read some thread on here that I can't find that some fellow with an old Ford put syn in his truck and got a bunch of leaks. That got me thinking to when I had a Z28 in 2000 and tried syn and got my rear main seal leaking.

Is there no way around this? I had five jugs but emptied one of them into quart bottles for top off and easier pouring. Would it hurt to use these as top off in case I have oil consumption, or, I might just relegate the syn to OPE and oil cans. But, if a quart of syn in a six quart sump won't hurt much, I may do that.


Vehicle in question has 165k and was probably ran on Dino and I'm probably going to try yearly or bi-annually oil changes with Valvoline conventional and a FU since I probably will put between 2-4k yearly, but will most likely use the Oil change monitor.

 

[Donald]

It has happened but very rare. Typically with older types of gaskets.

What happens is that a false seal of crud builds in front of the actual seal and the false seal does the sealing, not the actual seal. The actual seal if its made with older types of materials then dries out. The synthetic oil cleans up the false seal and the dried up seal then leaks a bit until it gets conditioned and then the leak stops.

Its never happened to me but thats the theory.

 

[WobblyElvis]

I have a 99 dodge caravan. I put synthetic oil in it for the first time two years ago. It sits in my drive way now with a pan under it to catch the oil leaks. I'll never put synthetic oil in an older vehicle again. Why take the risk if conventional oil will let the engine live as long enough?

 

[RhondaHonda]

I had a 1990 Mustang GT and in 1999 I put Castrol Syntec in it. There were a lot more oil spots on the garage floor afterwards. The car had about 60,000 miles at the time.

 

[mjk]

Same here. Ran M1 in my Camry, when it had about 170k on it. Same logic for the resulting leaks; it cleaned out the 'false seals' on a car that was 15 years old at the time

 

[Scout1]

Hummm... I'm struggling to understand why today's synthetics cause or accelerate oil leaks given that most of today's synthetics are Group III, right? I guess some do have PAO in them, perhaps even esters (the Great Mystery!) and those may cause some issues. But in general, the Grp III oil molecules are just more uniform as I understand it. I guess they must also be smaller molecules so they seep past seals easier?

I swore the first time I put synthetic in my Honda, the clutch developed a cold chatter. "Oil must have gotten past the rear seal and onto the clutch" I thought. But... maybe it's just coincidence. The clutch was getting old! To the guy with the Caravan, I also have a 99 Grand Caravan with the 3.8. I Ran some Pennzoil Platinum through it and didn't notice any difference at all. It was the same 10w30 the engine calls for and the rig had about 95k miles at the time.

Maybe it's all in our heads!

 

[WobblyElvis]

Every time I have put a group 3 synthetic in an older engine, the new oil seems to dissolve old deposits that have accumulated in the engine over the years. I've seen this happen even when I have added only a single quart of synthetic oil to a conventional mix.

I'm pretty sure the leaks I have seen with synthetics were due to the cleaning action of synthetics, they are not "new" leaks. My Caravan has a 3.3 [same block as 3.8]. It ran a little noisy with the synthetic.

 

[Nick1994]

Yup, my 97' Camry last year already had an oil leak, after putting some of the good old Pennzoil Ultra in it the leak got worse. I didn't care the car was 17 years old.

 

[HerrStig]

Originally Posted By: WobblyElvis
I have a 99 dodge caravan. I put synthetic oil in it for the first time two years ago. It sits in my drive way now with a pan under it to catch the oil leaks. I'll never put synthetic oil in an older vehicle again. Why take the risk if conventional oil will let the engine live as long enough?
Did you check the PCV system?

 

[HerrStig]

Originally Posted By: Nick1994
Yup, my 97' Camry last year already had an oil leak, after putting some of the good old Pennzoil Ultra in it the leak got worse. I didn't care the car was 17 years old.
Crud build up can CAUSE oil leaks, for example past valve stem seals when the stem cruds up. Running synthetic from the start can reduce such problems. Maybe it's too late for your 97.

 

[UNC017]

Another legend that will never die. :-/

In very rare cases, a synthetic oil may leak a little more readily than a conventional because of different surface tension characteristics, but its the exception more than the rule.

If "crud" is plugging a gasket and preventing oil from escaping, is that a good thing anyway?

 

[turtlevette]

I too thought the synthetic causes leaks was an old wives tale

But,

My 79 Trans Am is leaking with Mobil 1 Turbo Diesel Truck.

How many more do we need to add to this thread to start believing.

 

[camrydriver111]

Originally Posted By: 440Magnum
Another legend that will never die. :-/

In very rare cases, a synthetic oil may leak a little more readily than a conventional because of different surface tension characteristics, but its the exception more than the rule.

If "crud" is plugging a gasket and preventing oil from escaping, is that a good thing anyway?


Whatever the reason is, the end result is more leaking.

 

[steveh]

In the early 90's I used synthetic in three new cars. I had nothing but problems with leaks. I had many seals and gaskets replaced under warranty. In 2008 I tried synthetic in a new Corolla and never had a problem.

 

[zeddy]

My anecdote fwiw

1997 BMW m3 allegedly ran on Valvoline 20w50 conventional per prior owner. Cat had 210k when I bought it. I did one oil change with Valvoline 20w50 conventional, car didn't leak but did burn a quart per 1k.

After reading about the benefits of synthetic and rotella t6, I switched to synthetic and within several hundred miles, began to notice oil leaks. I changed out the valve cover gaskets, including the spark plug tubes, and the oil filter housing gasket. Also changed out the pcv and vanos oil feed tube. This helped cure most of the leaks, but the car would still leak a little bit of oil.

My guess is the old seals had deposited crud that prevented the leaks from showing. Syn cleaned it somewhat and leaks started appearing. If you plan on keeping the car and want it running in tip top condition, syn would be good to know which gaskets might need replacing.

For me, I'd rather not know and just continue with what works.

 

[deven]

Next OCI I'm adding some gun powder additive to my oil and let it hunt for leaks.

 

[mjk]

I think if you read the responses, you'll understand we realize that SYN oil isn't CAUSING the leaks; rather the increased levels of detergents are cleaning crud out that is, in essence, keeping older vehicles from leaking -- i.e 'false seals'.



Originally Posted By: 440Magnum
Another legend that will never die. :-/

In very rare cases, a synthetic oil may leak a little more readily than a conventional because of different surface tension characteristics, but its the exception more than the rule.

If "crud" is plugging a gasket and preventing oil from escaping, is that a good thing anyway?