Synthetic oil in an older engine?

[loves_off_roading]

I don’t mean to start up the great oil debate again but I probably am. Anyway let me get to the point. I recently came across an article on the internet that didn’t recommend using synthetic oil in older engines. Here’s the site:

http://www.samarins.com/maintenance/engmain.html

Is this baloney? Or do you think this article is right?

Discuss…

Right now I use Mobil 1 Full Synthetic on a 3.7 with 85,000 miles
Maybe I should switch to semi synthetic the next time to get the best of both worlds?

 

[jnaut]

Largely been debunked. There's some talk that in the early days of synthetics, they didn't have certain additives that caused the seals to 'swell' properly which may have seen older engines begin to leak.

What has caused this myth to perpetuate is that people switch to synthetic oil on their 149,000 mile engine, and a year or two later, they see a leak and attribute it to the synthetic oil. that reasoning is what's known as post hoc ergo propter hoc reasoning. "After this, therefore because of this". The fact of the matter is their engine was fated to start leaking soon anyway, and had nothing to do with synthetics.

I have heard that switching to synthetics after years of using mineral oil will cause old mineral oil deposits to 'lift up' and float around in the engine, and therefore some sort of 'flushing oil' should be used first. I have no knowledge if this is accurate or not.

I switched to synthetics at 82,000 miles with no preparation. Frankly, I'm not concerned. If my engine assplodes in the next 200,000 miles, I'm sure it was because I switched to synthetics. :O

Now, break out your popcorn and let the debate begin.

 

[belvedere]

You will be fine...switch with confidence. If you have concerns, Mobil does offer M1 High Mileage oil.

 

[tjkj2002]

The big issue is older engines,'70 and older,used a different material for the seals which synthetic likes to swell.Newer engines use a different material that synthetic doesn't swell.So if you have a '70's era engine with OEM seals you will have a issue but if you have re-sealed that engine with new seals you will not have a issue.

 

[DJSKJ]

Be cautious with the synthetic blends. No standard has been set on the ratio of mineral and synthetic in a blend, i.e. it could be 99 parts mineral and 1part synthetic to be considered a blend. I would stick with one or the other.

DJ

 

[ridenby]

Bought Libby with 120000+ miles,switched to syn. now have 192000+ miles,change at 3000m,use FL1A,or equivalent size filters-just cause I like to-no problems,knock on wood.

 

[loves_off_roading]

"switched to syn. now have 192000+ miles"
thats great to hear ridenby

I'm looking forward to you hitting 200k. I'm sure you'll let us know.

 

[ChiefRudy]

the old engine stuff is crap. My fiancee bought her 2002 KJ used with 125K on it. It never had synthetic until i put it in. the Previous owners let the engine go to hell and it was loaded with sludge and the O2 sensor kept going off.. The Synthetic cleaned the engine up pretty good b/c sludge was pretty much gone after that and the engine ran and sounded 10 times better

 

[loves_off_roading]

My baby's lucky I bought her. The pevious owner hardly did any oil changes at all and it had a sludge buildup as well. The Mobil 1 is doing a good job cleaning her out tho.

 

[JJsKJ]

94 XJ, Notorious for leaking regardless of miles, (w/ about 165K on it when I got it) Had a RMS leak when bought, Fixed that plus new pan gasket of course, and added Amsoil which has been it's oil since then, now w/ close to 200K on it, and no leaks since the RMS was fixed. No other gaskets changed since then either.

99 TJ, had a RMS leak when we bought it, changed it to same Amsoil 10w30 in XJ and leak has slowed over time. Still needs to be fixed as it does drip on my driveway but nowhere near as bad as when it came home a couple years ago.

 

[Auberon]

There appear 2 enterpretations evident in this "discussion" in its youth.
What actually constitutes an "older" engine.

The question is: Is it either higher mileage, newer vehicle or a 64 rollscnardly? As I read these posts confusion reigns thru people trying to have an opinion on every permutation possible.

Seriosly: Can we stick to the one topic, please?
I read this as a question about changing oil types on a slightly (stressing slightly) run-in but maintained motor.

Am I correct?
If yes, then that should be the basis of any discussion, should it not?
Hey Jnuat: no sarcasim, thanks for the latin....very poignant.

Cheers
Auberon

 

[jnaut]

There appear 2 enterpretations evident in this "discussion" in its youth.
What actually constitutes an "older" engine.

The question is: Is it either higher mileage, newer vehicle or a 64 rollscnardly? As I read these posts confusion reigns thru people trying to have an opinion on every permutation possible.

Seriosly: Can we stick to the one topic, please?
I read this as a question about changing oil types on a slightly (stressing slightly) run-in but maintained motor.

Am I correct?
If yes, then that should be the basis of any discussion, should it not?
Hey Jnuat: no sarcasim, thanks for the latin....very poignant.

Cheers
Auberon

You are correct, I noticed this too. "Older engine" pre 1970 etc. and "Older engine" - High mileage.

Since this is a Jeep forum, I'm assuming the OP meant "High mileage KJ engine". I feel relatively sure he wasn't speaking about his Plymouth Duster.

 

[J-Thompson]

Maybe this will help maybe not but I feel it is relative
I have a company truck ,F250 5.4L gas
The first was an '02 ,before that I had a Dodge
I ran Dyno oil until at about 90K it was burning oil at a rate of 1 QT per 1000 miles
mind you it was not smoking at all so unless you check the oil like you should but most do not you would not know
I am a nut for the 3K on dyno oil and 6k on syn
I made the switch to syn ,mobile 1, and the rate of burn dropped to 1 qt per 3K
this truck is still in service with over 220K on it and still running good
just that I do not drive it
one of the other 2 '02's has 188K on and and the switch was not made until over 150K
so the rate of burn is higher about 2 qts per 3K
the last '02 was driven by some one who ,#1 believed that "syn oil is a bunch of BS and a waste of money" he also believed that "changing your oil every 3k is a waste of money you will be fine going 10K"
well his just squeezed out 200K when it needed a new engine

My new truck is the same F250 but an '09 model
I have run syn from the first oil change and will do it as long as I own the truck
Ford says 7500 miles on dyno oil I say ok sure but I will waste my money and get it changed with full syn every 6k
mostly because I now average 3K per month and know good and well that I will be driving this truck when it has well over 200K on it

so you decide
is the switch to syn a good idea?

oh as a side note
my wifes new ride ,VW Tiguan 2.0T, requires Mobile 1 syn every 10K
I go every 5
The 2.0T is a high reving engine and uses the engine oil tolube and cool the turbo
with the rep that this engine has in the "tuner" world I figure there must be something
to full syn

 

[tjkj2002]

There appear 2 enterpretations evident in this "discussion" in its youth.
What actually constitutes an "older" engine.

The question is: Is it either higher mileage, newer vehicle or a 64 rollscnardly? As I read these posts confusion reigns thru people trying to have an opinion on every permutation possible.

Seriosly: Can we stick to the one topic, please?
I read this as a question about changing oil types on a slightly (stressing slightly) run-in but maintained motor.

Am I correct?
If yes, then that should be the basis of any discussion, should it not?
Hey Jnuat: no sarcasim, thanks for the latin....very poignant.

Cheers
Auberon

Old engine = old engine like a pre '80's engine(oler then most on this board I suspect)

High mileage engine = high mileage engine

Where is the confusion?

 

[jnaut]

Old engine = old engine like a pre '80's engine(oler then most on this board I suspect)

High mileage engine = high mileage engine

Where is the confusion?

The op referenced an old article in direct conjunction with his KJ being at 85,000 miles. I suspect that's where the confusion comes in. As I said above, I seriously doubt the OP was asking about his plymouth duster.