STP oil additive with Zinc - opinions, please ....

mtnmankev · May 15, 2020

While it is well known that oil additives will not replace mechanical wear and issues to cure problems, we do realize the importance of zinc ZDDP in our engine oils.
Most ZDDP additives are very expensive, so a more affordable alternative is needed for those on a tight budget.
I saw STP oil additive with ZDDP for $2.88 which makes the price right, but would it cause issues in an engine that is not worn out ?
And after doing some research, I find the claims that too much zinc can actually cause an increase in engine wear, but the makers of the additives don't state on the label how many ppm their product provide, to keep the zinc level in the safe and proper range ...
Any thoughts and opinions are welcome greatly appreciated.

Dutch Rutter · May 15, 2020

I'm not sure about the STP stuff. But I've been running this stuff on my rebuilt flat tapper 350. No problems at all and haven't noticed any flakes during oil changes. Lucas should know their stuff.

https://www.summitracing.com/parts/luc-10687

My machinist told me that oil manufactures do not recommend running any additive in their own oil, but they do sell these additives. The stuff that already has zddp in it, is at a good mixture for its designed use.

Also 6qt for $38.00 I feel is pretty decently priced.

DoubleDingo · May 15, 2020

Valvoline conventional oil has zinc, and valvoline racing oil has a higher level. I run conventional and don't have any issues, and both trucks have had cam replacements. Cams were replaced as upgrades, not from wiped out lobes. I mention the new cams because they are still fine. Heck, the cam in Crusty Biscuit coincided with a head swap. Broke in the cam, drove the truck around town for about an hour, changed the oil, and road tested to Texas and back. No flakes in the oil, lifters still in adjustment, and this truck has been driven thousands of miles since that cam change in 2017. The '81, similar, vortec heads, then a cam swap later, and 6 years later still running strong with no issues. Both engines run on valvoline conventional 10w30 and purolator filters.

Catbox · May 15, 2020

I have used the STP stuff for a while in my daily which is a 1973 VW Bug.

I don't notice any difference at oil change with or without the stuff in the car.
It runs a way old mystery engine from my buddies bus.

I also run the inexpensive WalMart oil as it is cheap.
I put loads of miles on this thing every year.

In the truck we put the same STP stuff in just for added protection.
Same inexpensive house brand oil goes in to it.
Runs like a clock.

mtnmankev · May 15, 2020

I always ran Valvoline conventional for many years, with NO issues ......
I am curious where the zinc level is at in their oils of today .
When I bought a motorcycle and started to use Castrol GTX, I found that both are equally good oils and have run Castrol since in all my gasoline powered equipment.
I don't know what level if any, of zinc is in Castrol, but i won't complain about how well it has protected my engines.
I don't know if Quaker state or Pennzoil EVER got their act together and fixed the high parrafin problem in their oils, but to this day I still do not trust either of them due to the crud levels i found in engines way back in the day.

DoubleDingo · May 15, 2020

I forgot to add, my '91 jeep is a flat tappet engine as well. I have never run any special additive in it and the engine still runs strong with 220k on it. Doesn't burn or use oil. It too is on valvoline conventional and purolator filters.

DoubleDingo · May 15, 2020

mtnmankev said:
I always ran Valvoline conventional for many years, with NO issues ......
I am curious where the zinc level is at in their oils of today .
When I bought a motorcycle and started to use Castrol GTX, I found that both are equally good oils and have run Castrol since in all my gasoline powered equipment.
I don't know what level if any, of zinc is in Castrol, but i won't complain about how well it has protected my engines.
I don't know if Quaker state or Pennzoil EVER got their act together and fixed the high parrafin problem in their oils, but to this day I still do not trust either of them due to the crud levels i found in engines way back in the day.

I think the valvoline conventional is the one with enough zinc to do the job of the old oils.

shiftpro · May 15, 2020

Rotella T4 has zinc and I have run it for years, engines are still running... it's cheap at Walmart.

DoubleDingo · May 15, 2020

shiftpro said:
Rotella T4 has zinc and I have run it for years, engines are still running... it's cheap at Walmart.

I forgot about rotella

JoeR Jr · May 16, 2020

I stopped using STP when I saw how bad it made my oil sludge in the heads. Granted it was many years ago, and the oil was way more paraffinic in those days, but I never went back to it after that. Any engine that I have that needs better lube gets BG Motor Oil Additive put in it. I don't do it on any vehicle running a cat though.

Joe

1987 GMC Jimmy · May 16, 2020

Side note, I had been using STP filters in my car because they were cheaper than Delco, and they used to be made here not that long ago. Well, they’ve switched to Chinese at some point, but I can’t say exactly when because I wasn’t paying close attention. I guess with Fram being trash, your only USA-made options are Wix/NAPA Gold, Delco, and K&N. I’ll probably bite the bullet and switch back to Delco in-store or order them in small bulk online. Also, the STPs don’t have the bypass valve provision and the Delcos, at least the PF454s that I need, do.

mtnmankev · May 16, 2020

I have been running Fram PH373 filters for many years and never had an issue with them.
MAYBE, being twice the size of a "normal" oil filter made the difference.
I am thinking of switching to Wix or Napa gold extended filters when I freshen up my engine in a couple months.
Would be nice to get an additional 20 years of service from the engine that I built 20 years ago and used hard.
And I have decided NOT to run the STP oil additive in the critical Chevy truck engines, but will bite the bullet and run Valvoline oil and add some straight ZDDP additive.
I will use the STP w/zinc additive in the Samurai that needs the oil pressure increase, it needs to be rebuilt anyway and as long as it will keep running for now I'm happy.
Talk about weird factory specs, at idle with warm engine, oil pressure in the Samurai is almost zero, but factory specs for the engine say 30 at 2,000 RPM is acceptable.

80BrownK10 · May 16, 2020

All oil still has zinc, they have just dropped the levels. It's still acceptable at the current level as I understand for flat tappets that are broken in. The problem is that the zinc dissappears as the oil gets used up so it's not as long before the zinc levels fall below the protection threshold needed.

Rotella has it but not at the levels it use to i think is what I read. If you find the older rating diesel oil , older than the current rating...I can't remember which one that is now, it has less zinc the the rating just prior. I will go look at my bottle. I found that tractor supply company brand traveler diesel oil is the older rating and should have more zinc because of that. And both will have more than current 10-40 or 5-30 or10-30 oils you may use.

I found a few months ago an article that listed zinc levels from oil analysis of all the major brands of oils. Walmart oil was a good performer in the test if I remember right. It was a good article and had good info.

idahovette · May 17, 2020

80BrownK10 said:
All oil still has zinc, they have just dropped the levels. It's still acceptable at the current level as I understand for flat tappets that are broken in. The problem is that the zinc dissappears as the oil gets used up so it's not as long before the zinc levels fall below the protection threshold needed.

Rotella has it but not at the levels it use to i think is what I read. If you find the older rating diesel oil , older than the current rating...I can't remember which one that is now, it has less zinc the the rating just prior. I will go look at my bottle. I found that tractor supply company brand traveler diesel oil is the older rating and should have more zinc because of that. And both will have more than current 10-40 or 5-30 or10-30 oils you may use.

I found a few months ago an article that listed zinc levels from oil analysis of all the major brands of oils. Walmart oil was a good performer in the test if I remember right. It was a good article and had good info.

Too many "I thinks" here, I think I'll just keep on adding my GM EOS to my old cars

peats · May 18, 2020

if you are running a flat tappet cam and not adding zinc you are simply rolling the dice. yes some will get lucky and get long service on straight conventional oil, i was not so lucky. my engine builder proposes using rotella t4 and in addition i add 4 to 6 oz. of lucas cam break in lube with every oil change. the lucas is not expensive and adds a lot of zinc. i do not recommend this procedure if you have a cat as that is the reason the zinc was removed from motor oil in the first place.

STP oil additive with Zinc - opinions, please ....

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