High-ish Mileage Synth Oil Switch - SMOKE

[gamatt]

So I'm at 90k, ready for next oil change. Head into Wally World to buy Valvoline High Mileage Synth Blend I've been using but they are out, so I grab some Mobil 1 Full Synth. Two days later, car smokes at EVERY startup and at the first few stoplights when warming up I get a puff of smoke as I start to move, but not under full acceleration.

After owning the car for a year and 10k miles I can count on one hand the number of times that it has smoked at startup and NEVER at idle at a stoplight. So consider this a word of caution about switching to full synth now that some of these cars are getting up in mileage. I found some of the trusty Valvoline, so now I get to drain out $35 worth of M1 gold.

[rich1]

The full synthetic oils are thinner than the blended oils ,thats what is causing the smoke.

[311-420]

so youve always used a syn blend, never full syn. now you tried full syn and get smoke?

[gamatt]

Originally Posted by 311-420

so youve always used a syn blend, never full syn. now you tried full syn and get smoke?

From new to 80k I didn't own it, but the Carfax mentioned quick lube type places, so I'm assuming mostly dino oil there. I changed the oil when I bought it at 80k and then at 85k with Valvoline Max Life semi syn, then Mobil 1 full syn a few days ago.

So it's more like dino->semi syn->syn.

[Mach916]

Originally Posted by rich1

The full synthetic oils are thinner than the blended oils ,thats what is causing the smoke.

[Bill Hamilton]

Originally Posted by rich1

The full synthetic oils are thinner than the blended oils ,thats what is causing the smoke.

I agree, did the same on a high mileage second car a few years ago and the same thing happened. Changed back to dino oil and it just has the normal slow leaks now. Synthetic are much slicker and thinner that they can leak through the smallers areas that a dino oils can't. If you switch to synthetic's, you need to do it early in the engine's life.

[Kelly@Livernois]

Its probably valve seals. Stick to what you have been using.

[blown03Mach1]

Is not 5W20 the same thickness regardless of it being conventional or syn? I thought that is what the numbers represented. In the case of the 5W20, the oils characteristics when cold are of a straight 5 weight oil, but once the oil is warmed up, it flows like a 20 weight.

If that were true, then why would it matter about what type or who made it as long as it was the same weight?

I am sure that there is more to it then that and I know someone will correct me if I am wrong.

Bottom line, if it were me, I would switch back to your old oil if it makes you feel any better. As for my car, it does have a valve guide (#8 cyl) that allows oil to seep past during long idles or sometimes when shut down. I changed out the stem seals 3x with no luck and took it to 4 local shops and all told me it was not worth the money to fix until you plan on pulling the motor to build.

Annoying... yes

[gamatt]

Well strangely enough, this morning no smoke at all.

[jonw357]

The exact same thing happened to me in my 93 LX 5.0. Swapped to full synthetic oil and smoked like a **** freight train. Swapped back to dino oil and it slowly stopped smoking. Never smoked till I put Synthetic in it. Put it did have 100,000 miles on it.

[gamatt]

Originally Posted by gamatt

Well strangely enough, this morning no smoke at all.

No smoke at all when I went out to lunch earlier.

[Kelly@Livernois]

Maybe it was acting like Sea Foam.

[Locutus]

I was told that full synthetics actually have detergents that dissolve regular dino oil. So if you switch at higher milage it dissolves oil deposits that are in gaskets and such, causing leaks or smoking. Don't know how much truth is to it, but I have always just run synthetic.

[gamatt]

Originally Posted by Kelly@Livernois

Maybe it was acting like Sea Foam.

I don't know, maybe.

Drove it 30 miles tonight and no more smoke!?!?!

[gamatt]

Originally Posted by Locutus

I was told that full synthetics actually have detergents that dissolve regular dino oil. So if you switch at higher milage it dissolves oil deposits that are in gaskets and such, causing leaks or smoking. Don't know how much truth is to it, but I have always just run synthetic.

There's an oil commercial on tv I've seen that shows that.

[311-420]

<------------ would like to hear the colonel's explanation

[blown03Mach1]

I am fairly certain that all oils contain detergents. Not sure if it mandated by the feds like detergents in gasoline or how much idetergent is in each brand of oil.

[006]

Thinner/slicker oil is easier to get sucked into the intake from the PCV mostly after some high rpm driving.

After sitting overnight, the accumulated oil sitting in the intake burns on startup, and you see a puff of smoke.

Same effect as spraying some WD-40 into the throttle-body.

[03mach69mach]

I had a similiar thing happen on my '69, put a synth blend in it and found that valve cover gaskets (cork) started leaking like crazy, changed back to straight dino and no leaks. Maybe it's the Mobil 1 that is your problem, not the full synth.

From my view, I am beginning to wonder if Mobil 1 is all it's advertised to be.
Wife purchased a BMW 330i that has had Mobil 1 0W-40 it's entire life. Currently at like 85,000 miles. You should see the crud under the valve cover on this one! Not impressed. Also, been looking an oil forums and have seen several people over their who have tested their oil (Blackstone) finding higher concentrations of certain metals, which they say are wear of valve guides & bearings with the new high mileage Mobil 1 stuff.

In my newer Fords, I will continue to use the Motorcraft 5W-20 blend (one of the cheapest name brand oils at Wally World).

[rich1]

Originally Posted by Mach916

Read other posts to get smarter.

[Bill Hamilton]

Originally Posted by Mach1Marauder

LMMFAO @ SUM U GUYS!

..................
Syn oil in NOT thinner than dino oil with the same viscosity. That's funny!

What is normally used now days, 5W-20, is “thinner” than the 10W-30 which was normally used years ago in performance cars. Today’s engines are basically blueprinted from the factory compared to engines from 30, 40, or more years ago. As internal combustion engines for passenger vehicles have been forced to become more fuel efficient, less polluting, smaller, and longer lasting, their lubrication needs have changed dramatically. These changes in the engines have required the development of multi-weight detergent motor oils that are suitable for the tighter clearances, higher heat, and higher RPM of these engines. The Also there can be no question that synthetic’s are slicker or slipperier than conventional oils.

http://www.nordicgroup.us/oil.htm#Detergent%20Oil

[rich1]

Originally Posted by Mach1Marauder

LMMFAO @ SUM U GUYS!

Kelly nailed it. It was most likely the valve seals. The syn has more detergent action and is able to keep junk in suspension better than dino. The syn cleaned the deposits from the seals and oil was able to get past the seals a bit more. The oil sitting on the seals over night seeped into intake track IN THE HEADS and sucked up the combustion chamber upon start up. As the engine warmed up, it sealed back off. With a bit of time, once the seals were clean, the oil was able to get back in a "swell up" the seals again.
This is very common.
Syn oil in NOT thinner than dino oil with the same viscosity. That's funny!

Funny...A few years ago a mag Popular Science did a viscosity test between Syn and Dino oil. The syn oil was thinner in the tests from start to finish. At lower temps to higher temps the syn oil remained thinner. The main thing they said was the syn oil produced lower ash and stood higher temps. The tests were being done to compair flow properties for high dollar equipment in Alaska. I agree that the valve stem seals can be bad too. But alot whole lot of people have complained about full syn causing more leaksand smoking no matter what the mileage was. Castrol started making a blend oil in responce to this ,according to their Field Rep.

[rich1]

Originally Posted by Mach1Marauder

LOL...........Do you realize how refined the dino oils are today?
We're talking CURRENT technology.
It's really an oxymoron of sorts. The dino oils are by far more refined than ever before and MOST the so called syns don't come from a TRUE synthetic base.

Im not an expert , just what the Rep said . He also said almost all the Syn oils are a produced by a process called "cracking". Like you said , not a true syn base. He said that Castrol Syn-Tec was produced this way but would not confirm the new Castrol Edge oil was or was not !

[311-420]

So, the synthetic's detergent cleaned the sludge on the valve seals left by the non-synthetic blend. This allowed for a small gap between the valve seals and heads and allowed a small amount of oil to seep through and get burned...once the engine warms and things expand, it gets sealed back off.

I guess that the synthetic would still be a good choice since the seals are now cleaned. I suppose it wouldn't really matter if he went back to a blended oil now, since the gunk has been removed and clearance has been made. Probably better to stick with the synthetic?

[Kelly@Livernois]

If I were to run synthetic it would be Pennzoil Platinum. Thats it.

However, I like to stick with a good ole FL-820S and some Motorcraft 5-20 syn blend.

My first post, I stated it was probably the valve seals, and to stick with what you are/were using. Of course, if you dont ever want smoke.

My second post, was...in a round about way, saying it was acting like sea-foam.

Those posts are basically my way, in short, of explaining what Colonel Bill explained. LOL