STP?

[cliffy]

Just curious if anyone uses (or should I say- has anyone ever heard of friends ) using STP in their airplanes?

[N601RX]

The 1st plane we purchased several years ago was a cessna 150. It only used a quart of oil in the 1st 25 hrs. After the 1st oil change it started using a quart an hr and fouling plugs continuously. We replaced the cylinders with new, but were later told the the previous owner was putting STP in the oil. I would not have believed it would have made that much difference, but something did.

[carusoam]

S-top

T-hink

P-lan

If you intend to add unapproved things to your plane's oil, it would be good to STP first... Stop, think, and then plan...

One of those memory things they teach people.

Best regards,

-a-

[kerry]

I've heard of using Marvelous Mystery Oil  but not STP.  I don't think there would be any harm or benefit using it in small amounts.  Just a waste.  Aviation oils have detergents already in it.

[cliffy]

Not using it just wondering if anyone has ever done it. I used to run it in my 65 VW for 100,000 miles. 

When i took it apart after swallowing the #3 exhaust valve it looked new inside. 

[StevenL757]

Just curious if anyone uses (or should I say- has anyone ever heard of friends ) using STP in their airplanes?

Has no place in aircraft engines. Common sense should prevail here...

[Alan Fox]

Basically STP is a thickening agent , that increases surface tension of automotive oil....If it is of an ashless dispersant formula , I don't think it could hurt , But again not approved.... 

[carusoam]

Logic of this thread...

1) engine parts wear...

2) worn engines lose oil internal to the cylinders.

3) oil in the cylinders burns and clogs spark plugs.

4) oil thickening agents keeps oil from easily passing through wear enlarged gaps.

5) unfortunately, thickened oil does not lubricate as well as the intended viscosity of oil that is recommended for the engine.

6) Oil thickener can minimize the loss of oil at the cost of not lubricating tight tolerance parts.

7) the example of a VW engine running 100kmi and looking like new while destroying a valve sounds like what you can expect of an air cooled plane's engine.

Other automotive examples... Valve guides wear and drip oil into the cylinder. Burnt oil blocks the spark plug. Fuel injector cleaner or heavy doses of intake cleaner can wash the build-up off spark plugs... (’87 firebird experience L98 engine)

If the logic fits...

Somebody is using a chemical agent to band-aid a physical wear problem. The cost is even less lubrication in unworn tolerances.

Valves are a terrible thing to get stuck in the O360. I had that experience too...

There is no magic behind most of these wonderous additive products. Find out what is worn and not working and get it replaced. It might be as simple as OH a cylinder...

Best regards,

-a-

[Alan Fox]

Anthony , I disagree , if you have ever handled STP, once it gets on something it does not get off , if you put a drop of it on a desk , and touched it with your finger , it will stretch like honey or taffy , The surface tension of it is truly amazing....In testing they have put it in oil and drained the oil , and driven cars 50 miles or better with the oil removed.....the only drawback I could see is if it is not ashless dispersant.....

[carusoam]

Alan,

I'm in the middle zone...

Zone 1) If it has data that supports it's use in our application (Ed Kohl style?)...

Zone 2) it clearly fixes the obvious problem somebody is having, but doesn't cover all the other bases (no data available)

I am reluctant to do things without all the data to support its use in our engines.

This is related to how easy it is to park a car on the side of the road compared to me landing a plane in a field...

My FB can find safe parking using it's starter motor...I'm not going to try this with the IO550....

Best regards,

-a-

[N201MKTurbo]

STP is a ZDDP additive. Two reasons not to use it are:

Our aviation oils are Ashless meaning that they burn without leaving an ash. The ash will build up on valve stems and cause stuck valves. ZDDP will leave an ash and can lead to stuck valves.

ZDDP can reduce cam and lifter wear up to a point. More then 1400 PPM of it can cause pitting of lifter surfaces. Adding a bottle of STP will raise the level of ZDDP above this level.

[PTK]

I'm amazed at how gullible some people are! The psychological placebo effect at work!

Clueless folks believing they're doing the absolute best or purchased the most engine protection they can possibly get. Even worse, they get that warm and fuzzy feeling that they are so far ahead of the rest of the pack!

They ignore totally the advice of engine manufacturers and lubricant industry manufacturers.

They forget the fact that oil companies go to great lengths to develop an oil with prescribed specifications. It is not an easy task!

Adding garbage to it in such a nonchalant fashion can only be described as ignorant!

STP does not belong in ANY engine! After market additives do not belong in ANY engine!

What belongs in the engine is an appropriate engine oil that is of the absolute highest quality and used as prescribed!

[Alan Fox]

Yes the expert has spoken..

[Alan Fox]

Jim STP wont quiet the lifters on startup , I have been an Auto Mechanic for 35 years  , you may want to try about 6 to 8 ounces of ATF in the crankcase at oil change ,  I have been doing this for years on older cars , and it works about 90% of the time....You should consult with Peter first ......He is the expert...

[PTK]

Jim, I agree with you on most points.

I have trouble with the notion that additives can address issues not considered by manufacturer though.

Not to turn this into another camguard exchange but I don't buy into the notion that an aftermarket additive somehow can fill the shoes of what the manufacturer has formulated.

In other words manufacturers have considered corrosion and have addressed it.

They are not depending on camguard or waiting for an after market solution to improve upon their product!

[Marauder]

Jim STP wont quiet the lifters on startup , I have been an Auto Mechanic for 35 years , you may want to try about 6 to 8 ounces of ATF in the crankcase at oil change , I have been doing this for years on older cars , and it works about 90% of the time....You should consult with Peter first ......He is the expert...

I was really disappointed that Peter did come out on Saturday. Would have been great to discuss CamGuard, Garmin and all of his other causes.

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[DonMuncy]

Suppose that an oil manufacturer has a product that does 98% of what is desired. Then they figure out that to get that extra 2% protection, they will have to spend an additional $1 per quart. This will boost their cost such that they will have to either cut into their profit considerably, or raise their price substantially above their competition. What do you think their decision would be.

If you assume they would do nothing, how much more would you spend to add something to gain that 2%.

[KSMooniac]

Some of you might be surprised to learn that Lycoming specifies using some STP as a pre-lube during engine assembly. I just read that Saturday in THEIR overhaul manual.

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[PTK]

Suppose that an oil manufacturer has a product that does 98% of what is desired. Then they figure out that to get that extra 2% protection, they will have to spend an additional $1 per quart. This will boost their cost such that they will have to either cut into their profit considerably, or raise their price substantially above their competition. What do you think their decision would be.If you assume they would do nothing, how much more would you spend to add something to gain that 2%.

We can engage in hypotheticals all day long. They're excellent theoretical discussions for the classroom when we don't know the reality. Since we know the reality here there's no need to engage in hypotheticals.

But let's assume you sucumb to the psychological pressures and add an aftermarket additive to the oil. You did this for a reason: to alter the formulation of the oil because you feel you know better than the manufacturer.

What do your studies tell you about your new formulation? Does it potentially prevent the oil from performing to your original 98% hypothetical?

What have you gained? Nothing. In going after the 2% you sacrificed the 98%.

Is this what you want?

[cliffy]

Lycoming also says to use STP in a "potion" to lube the cylinder studs when you replace cylinders removed for overhaul. You have to use a "lubed thread" torque method to re- torque the cylinders not dry threads.

 

I used to work in the air racing field when I was very young (19). The P-51 I worked on hired the  "Miss Bardahl" mechanic crew to set up and crew the engine during the races. If anyone remembers, Bardahl, its an oil additive also. I have a picture somewhere (haven't seen it in decades) of the Bardahl crew pouring a 5 gallon can of STP into the P-51 oil tank. They said they preferred STP over their own stuff!  That was back when 100" MP was a BIG deal. We blew a lot of Merlins at 90 to 95 inches of MP. 

[cliffy]

BTW I don't think STP played a a part in the VW valve failure. #3 was the one that failed most of the time in early VWs (60s) because of poor cooling from the fan duct. I don't know how it burns but it sure made everything slippery.

Try this with it- take a clean blade screw driver and and pinch the blade between your fingers. You can hold on to it.

Now dip it in STP wipe most of it off and do the same thing. It will squirt out of your fingers, you can't hold it.  

[N201MKTurbo]

FWIW

MMO Bardahl and Rislone are different then STP. STP is an anti wear additive, the others are solvents intended to clean an engine. From what I've read they are very similar in formulation, they consist of 50 weight oil, jet fuel, mineral spirits and some have some xylene or acetone. If your AUTO engine has a stuck lifter, the solvent additives are sometimes effective at loosening them up.

My truck has 135000 miles on it and I add a QT of MMO the day before I have the oil changed. It seems effective at removing the gunk in the engine. I wouldn't run it all the time, I think it would be bad on the seals.

[bonal]

Amazing a debate on STP. Cam Gaurd I can see even MMO but STP. A couple years ago my F250 with 136k miles on it started to have a fuel pump failing in one of its tanks causing the engine to back fire and stall. I put a pint of MMO in and problem disappeared never came back. I will admit to adding a small amount of MO to my Cessnas fuel about every 3 or 4 fill ups that engine always ran great.

[jetdriven]

MMO is prett good at cleaning up lifters that rattle at startup. A small bit of grit or carbon gets caught int he check valve and allows the lifter to bleed dry after shutdown. Then the valves have clearance so the rocker taps on the valve stem until the oil pressurizes the gallery and takes the lash out.

[cliffy]

Anr sometimes it never clears out and they tap all the time. :-)