STP with zddp or modern additives

A friend told me that STP had zddp in it so I went out in the garage and looked at the gallon I have and yes it does,even though my motors were broken in before it was being reduced in the oil I have been thinking about adding some to every other oil change or once a year. So the question I have is would it be ok to use the STP or just buy the modern additive,I had about 4 gallons of the STP and used it for years keeping the worn out motors going until I could repair or replace and hate the thought of wasting it if it could be used to help the modern oils.

 

What if your friend is wrong?

 

It says right on the label that it has zddp in it,but how much I dont know.

 

I've always been a fan of STP , never have had a problem w/it in either new or old engines. FWIW , a little extra ZDDP can't hurt IMO.
dave

 

I've been adding one container (1/2 quart?) STP to each oil change on my old stuff with flat tappet cams for the last 5 or 6 years. Because I also read about the Zinc thing. I can say I have had no issues at all using it. I use modern synthetic oil which, I am assuming, does not have enough Z in it.

 

stp is great stuff, i wouldnt think twice about using it in anything that uses oil

 

Since I have it I would like to use it,I wish I would have know about the zinc reduction much sooner so I could have used it to protect the good motors instead of trying to prolong the junkers. I am getting my 55 Ford ready for the trip to Daytona next month and will put a little in and did put some in my 65 custom 500 yesterday that I recently changed the oil to see if it will do any good. Along with the trying to prolong the tired motors I have been using it in some mid 60s lawn tractors I use around the house.

 

Depends, IF it is SM or SN it doesn't, earlier SF it does. Some Royal Purple(for instance) is SF & some is SM. You just have to check the label.
There has been some discussion on weather STP blends in or just globs at the bottom of the pan. Some add it when engine is hot & running vs cold.

 

Most oils that are "Racing Oil" marked on the bottle contain the ZDDP additive. I use Valvoline 20-50 in my flattys. Works great.

 

Email STP corp.....the email address is on the bottle....they say to email them if you have any questions about their products. I did.

Let us know what they tell you....then I will tell you what they told me.

 

Used STP since 1972 in all my stuff. Works great, no problems.

 

I was just researching useing STP and http://zddplus.com/.

Read the red STP bottle for 4 cylinders was thinner viscosity and good...? Who knows

Im not sure about useing STP. Never have used it. I remember bad stories about it, in the old days

I have a couple nicely built SBCs I built years ago, with good miles on them in vehicles. Always did 3000 mile oild changes on them with 20-50 valveline or Castrol but additives in these oils probably have changed over the years.

Someone posted "too much zddp can be harmful" ...WTF?

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I to wrote to STP about the PPMS zinc/phospate (spelled wrong) .

1st reply from them. Out product has sufficent amounts of ZDDP for flat tappet, older engine protection,,,,,,,, blah, blah,,,,,,,.

I wrote back saying, fine and dandy it has sufficent amounts of ZDDP, but HOW MUCH?

2nd reply, our STP formula is perfect for older flat tappet engines,,,,,,, blah, blah, blah,,,,,,.

I wrote back a THIRD time asking,,,,,,,,. Exactly how many PPMS (what is the number) of ZDDP is in each can of STP?

3rd reply from STP Corp, was one word. "Enough"

A-boner, is that close to what they told you? A bunch of run-a-round double talk?

 

I too have heard about globs of it in the pan but its probably from using too much and not changing the oil regularly,on the bottle it said keep it at 10 percent.

 

Never had a problem with a 50's-70's engine, when mixing STP with the oil.

 

They said it (STP in the blue bottle) had enough zddp to make 4-5 quarts of "new" oil the same as 4-5 quarts of "old" (before they removed the zinc) oil.

 

I knew a circle track racer in the late 70's that used STP on rod and main bearings when assembling new engines. He helped me build my first 327 chevrolet with the stuff and that motor ran real strong for along time. I wouldn't use it for that purpose nowadays with whats available but that was his trick back then.

 

You got more out of 'em that what I could. I'd still like very much know the actual #. How many PPMS, 800, 900 1000, 1200, 1400, what!

 

I use it in my wires 2011 mazda 2 my 93 isuzu ute and my 59a. every oil change i have ever done and never had any problem. old tech still works

 

Back in the 60's and 70's I tore down several low mileage engine with the mains knocking. They had globs of STP hanging in the bottom end, usually all of the oil screen covered down to a small spot about the size of the end of your pinky finger. Odd thing the majority were Buicks, although there were a few other brands. After that the only way I would use it was warm the bottom of the tin can with a torch until it was thin, and then pour it in a running engine and let it run for at least 30 minutes. Even at that I would not put it in anything without a lot of wear on it already.

 

Back in my younger days, a good friend had a 66 SS396 Chevelle that was really wore out. So he put straight STP in it. Another of his friends rolled it for him, so I don't think he drove it that long that way. I do remember it backfired alot, fire all the way out the tailpipes! It was funny when he checked his (STP), couldn't hardly see it on the dipstick.
The old STP had alot of ZDDP, but the newer not near as much.

 

Back before the M/C chains got O-rings, I would heat up to boiling, (OUTSIDE, 'cause it would smoke and STINK) couple of cans of STP in a old pan. Soon as the STP had the consisity of water, place the chain in for a few minutes, then pull the pan off the fire.

When it was cool enough to stick my finger in the mess without burining, I would pull the chain out, hook a S shaped coat hanger in the last link, hang it up in a tree limb and let the extra drain back into the pan.

by getting the STP hot and thin it was able to seep inside the chain rollers. When cold it was thick enough to form a barrier to keep dirt/crap out.

Sprockets and chains lasted a lot longer, and didn't have as much 'throw off' on the wheel/whitewall.

Since STP Corp will only give a 'generic' answer to how many PPMS of ZDDP are in each can, 1200-1400 PPMS is what the flat tappets require. Their 'enough', what is required min enough, my enough, your enough, can be ANYTHING!!

Yes the correct' way to install STP, NO MORE than 20%, or If my 'siphern's' right one can of STP to a gallon of motor oil, have the motor up to running temp, even have a light bulb on the can of STP, or the STP hot and dump it in a running engine, then run that engine at hiway rpms for 20-30 minutes.

Better way, is to have the STP already mixed into a quart of oil, before pouring into a running engine. That way one can let the entire contents of the STP drip out of the can.

 

Amsoil! 10W30 Synthetic Oil Hot Rod Oil (Zinc Formula). No more adding bottles of addivitive to your oil changes!
J

 

I have a hard time putting 10 weight oil in anything.
I always figured STP was snake oil, but my machinest recommends it. Nope, I still don't use it.

 

Larry I was skeptical at first too. But I tired and made the plunge to Synthetic when I rebuilt the motor. I have great oil pressure when it is cold and hot. Car even runs cooler too. The synthetic definatley feels different to the touch too??

So so far I think that the change proved itself to be no problem at all. especially driving the car out to California from Toronto On Canada this summer.
J

 

Since the ZDDP is a metal in suspension in the liquid, I'm assuming it becomes impregnated in the metal surfaces like the cam lobes, lifters and bearings. Does it stay there permanently or after a while does the wear on these surfaces wipe the ZDDP back off and these surfaces need constant replentishment ?

 

Yes

It stays on a semi permanent basis or extended length of time. But it does wear off and needs to be replenished. Some residual will remain.

The parts of Zddp per million parts of Oil isn't very high. 1000 or so per million or 1/thousandth. Or one quart of 100% zddp per 1000 quarts of oil.

 

Valvoiine VR-1 Racing Oil has 1400 PPM of Zinc and 1300 PPM of phosphorous. I would rather use VR-1 then adding some kind of additive that leaves you with an unknown concoction by not knowing the actual numbers of Zinc and Phosphorous you have. I would also think a manufacturer claims would be more precise. I use VR-1 in all my SBC's, roller of flat tappet. Too much ZDDP is detrimental to engines as well. It creates acidic compounds that lead to premature bearing failures. No way I'd add some snake oil like STP to my engines and create an unknown concoction. Adding something to create higher oil pressure solves nothing and is only masking a greater problem. Manufacturers of engine oils spend millions of dollars on research and engineering to create the optimum blends of oil. I'll rely on them to come up with right amount of Zinc and Phosphorous to add. It's also cheaper then buying an additive. You can but Valvoline Vr-1 for less the $5.00 a quart non synthetic or less then $8 for synthetic.

 

I was another user of STP for many years. Actually until I started buying new cars and trucks. Then I figured modern oils were good enough.
But STP seemed to give better oil pressure and never hurt any of my old engines. I'd just pour it slowly into a warm engine after an oil change using it as part of the last can of oil.
My wife said it looks like honey. Actually they called it motor honey. Tasted like honey !
Hell maybe that's why my motor is still runnin! Actually I only tasted it on my finger. Wanna lick my finger ?

 

Rebuilt my Dads 389 Pontiac way back when. Only had about 40,000 on it. Dad regularly used STP. I had to beat the lifters out as they were covered in varnish. Dunno if it was the STP or what.