Lizard944

It seems that the department store "Big Lots," has bought out the last remaining stock of STP Four Cylinder Oil Treatment; the red bottle with the higher amount of ZDDP. Not the whimpy stuff in the blue bottle that's on the shelves today! Was $2.50/ea. I bought 10 but they must've had 100 on the shelf. ZDDP has been severely reduced in today's oil for newer vehicles, but is needed in our older cars. Apparently, the Feds think it shortens the lifespan of catalytic converters. Anything the Feds are banning has to be good. Anyway, get it while you can. I'll leave it up to you analytical types out there to debate the effectiveness of this product. All I know is that it's endorsed by some serious engineering gurus out there like Charles Navarro. Just want to let everyone know, who cares to indulge.
---Lizard

KuHL 951

You can also use Valvoline Racing VR-1 20W-50 dino. It still has the same ZDDP (.13%?) as the old school oils plus correct detergents for street use. Same goes for Shell Rotella T for diesels and several motorcycle oils. I never was a big fan of STP additives after having my manual transmission seize up on me in real cold weather.

MM951

Now that you mention Rotella T, it is on sale at Wal-Mart $11.50 for 4qts.

944Ross

Run the numbers; dilute the ZDDP content of the little red bottle by 6 qts of oil and it makes a negligible difference in the overall level of ZDDP; as I recall the STP is around 1200 ppm, divide by 12 (6 qts to 1 pint), gives about 100 ppm. About 1/10th the level needed to make a difference. (this is by memory, but I've done the calc and seen others who got the same conclusion).

Potomac-Greg

I used the VR-1 for my last track event in the Fall. I then needed to switch to a "lighter" oil for winter, and for the first time in my life, I actually saved the VR-1 for later use.

lovemyp-car

i used vr1 in my engine this summer, it ran great, the engine really liked it, but i didn't save it because it was quite dirty when i drained it. This was maybe the second oil i used in the engine after i rebuilt it, so there was still quite a bit of stuff getting washed out. I used the vr1 sae50 oil, it was very thick, which made cold starts a little more difficult, but it held very good oil pressure through high operating temps in the dead of summer...great stuff!

MAGK944

+1 Rotella T in the daily driver and Brad Penn in the track car, both provide all the ZDDP our cars need.

m73m95

I can't find where I read it, but I remember reading somewhere that the VR-1 contains LESS detergents than regular "street" oil.

I know it contains some, as it is not pure race oil, but for a DD, less isn't a good thing either.

Not to turn this into the typical "what oil do you use" thread... but.... Mobile 1's 15w-50 still contains the "old" amount of ZDDP, as well.

Marcquito

I'm all for ruining any components that have to do with emissions. I'll buy some tomorrow!

Lizard944

Well, you naysayers do what you want. The EPA mandated a severe reduction in ZDDP for ALL over-the-counter street oils. If you think that there are still some on the shelf with the original amount of ZDDP (wink, wink), then, by all means, buy it. The Red STP was yanked from the shelves because it contained too much ZDDP to satisfy the Feds requirement for a converter to last >100K miles. So buy what you "think" has enough ZDDP, or buy what you know has a hefty amount of ZDDP. The fact that it was pulled from the shelves is proof enough for me.

Potomac-Greg

So what happens to the converter with excess ZDDP? Does it clog or just go inert?

And more importantly, will it affect my converter if the converter is sitting on a shelf in the garage? ;-)

(My converter is in fact still installed, but as a Maryland "Historic Vehicle" no emissions inspection is needed.)

KuHL 951

I guess I'm a naysayer then and I'm not trying to be stubborn. The VR-1 Racing (street legal) still contains .13% zinc and .12% phosphorous. Show me any failure documentation or degraded oil analysis where those concentrations are not adequate for flat tappet applications. I'm not arguing but one bottle of STP ZDDP additive will not raise most of the new SM grade oils enough to matter and putting additives isn't usually a good idea on a properly blended oil.

Read up on aftermarket ZDDP additives and tell me they are a good idea: Click Here

Potomac-Greg

Let's also not lose sight of the fact that our 944s do NOT have flat-tappet valvetrains, so while the ZDDP may help us sleep at night (as it bathes and soothes our #2 rod bearings) we need it less than our air-cooled brethren.

KuHL 951

I was just trying to impress on the OP: Where are the failures in the even more critical flat tappet applications at the .13 Zn levels, not how critical it is for a 944. Personally I wouldn't give anyone 10 cents for any STP product that I planned to leave in my engine for a full 5K mile interval. I have some great gas magnets I can sell you though