Weight of oil?

[Chryco Psycho]

15 - 40 w diesel oil;s have added detergents to combat soot negating the benefit of extra zinc

[mojavered]

20-50w oils have lower detergent levels so the oil needs to be changed more frequently

What about 50W?  Does it have a lower detergent level also?  Is it to heavy for a street motor?  It is always available at the auto parts store.

[Chryco Psycho]

20-50w oils have lower detergent levels as it is considered a racing oil / short life span

[1970 RT Challenger 1970]

Are you better to buy a ZDDP additive or buy the oil with ZDDP in it?

How many ppm (parts per million) do you need of phosphorus and zinc (ZDDP) in your oil? Can you put in too much ZDDP additive if your oil already was made with some in it?

[Chryco Psycho]

you need a inimum of 1600 PPM Zddp , additives are fine , using too much as in above 3000 ppm can be an issue but most oil on the shelf is between 400 -600 ppm now

[1970 RT Challenger 1970]

no, it is low on zddp, but, Mobil1 15-50 has a good dose.

What would the oil change interval (miles) be with the Synthetic Mobil 1 15W50 with 1200 ppm Phosphorous and 1300 ppm Zinc?
Assuming Street/Highway use?

Is this Correct: Any Engine with a Carb (Hydraulic Lifters, Pushrods, Single Cam, V8 Engine, 4 Door Passenger Car) from about 20 to 30+ years back should use the higher amounts of zddp in the oil?

http://www.hotrod.com/techarticles/engine/flat_tappet_cam_tech/index.html

Thanks.

[Changin Gears]

15 - 40 w diesel oil;s have added detergents to combat soot negating the benefit of extra zinc

What side effect do these detergents cause?

[Chryco Psycho]

detergents counter the effects of the ZDDP by tending the clean away the zddp coating
any Flat tappet cam engines especially with carbs need more ZDDP than any of the off the shelf oils have except the racing 20-50 non SM oils
Z-Alt oils have also got an extreme pressure additive good for 3000 PSI

[greenzeppelin]

has anybody had experience with this pennzoil 20w50...

link:   http://docs.google.com/viewer?a=v&q=cache:5R4ha9lMGlAJ:www.mil-specproducts.com/Documents%255C1124_PDS59.pdf+pennzoil+20w50&hl=en&gl=ca&pid=bl&srcid=ADGEESg5LRcX06D8VSqEvu-_8IrB6JWJqYSupebVxiMnHpTXcjJpAU5vveKpJI5ygjq5Cob17GodX2bBqAH6Dethnu6Ydigf1UMGnbvrsWhlZxpmTXPrajUPgn3PdEHAHZg4UTuOKCE1&sig=AHIEtbSDIG9TDT1axZ1eMoveksavFXyt2w