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  Topic Review (Newest First)
02-16-2020 04:08 PM
zjosh93
Quote:
Originally Posted by Gregory98zj View Post
so just how much do I need to use for 7 quarts of oil.im currently using 7 tbs.so in tbs measures how much would be correct.
Depends on the oil you're using. I use Shell Rotella T4 15W40. It has 1200 ppm ZDDP already. That'd be real close to the limit. I'd use less ZDDP additive with that oil. (Or none at all as I actually do)

If you are using any of the gasoline engine modern oils they probably have less than 800 ppm ZDDP so you'd be fine with your 1 tbsp.
02-15-2020 09:37 AM
Gregory98zj so just how much do I need to use for 7 quarts of oil.im currently using 7 tbs.so in tbs measures how much would be correct.
02-14-2020 06:12 PM
zjosh93
Quote:
Originally Posted by Gregory98zj View Post
SORRY that was supposed to be 1tbs per quart of zinc.so 7 tbs total.
That works out to about 780 ppm extra ZDDP. Double check that your oil doesn't have more than 1,200 or so already (unlikely) or the ZDDP can start to attack grain boundaries in the cast iron.

A bit off topic I know.

I don't think the ZDDP is the overheating issue though. Zinc and phosphate poison the cat so it stops reacting. It just stops working.
02-14-2020 04:05 PM
Mr. Puddles
Quote:
Originally Posted by Gregory98zj View Post
no it will only pull codes.im was getting around 19 to 20 mpg.now about 15.
Quote:
Originally Posted by Gregory98zj View Post
I only use 1 tbs of Lucas engine break in oil addative which is zinc or zddp.

The drop in mpgs could be due to the cat having issues. Id say spend the cash and get it swapped and we can address and additional issues then. Until then we are doing with skewd data
02-14-2020 04:03 PM
Gregory98zj MR PUDDLES. I'm 100%sure theirs something in the pipes.just a big constriction in the cat.my pipes are about 7 months old.the cat wasnt rattling or getting hot then so I only replaced the pipes and muffler.
02-14-2020 04:00 PM
Gregory98zj SORRY that was supposed to be 1tbs per quart of zinc.so 7 tbs total.
02-14-2020 03:54 PM
Gregory98zj I only use 1 tbs of Lucas engine break in oil addative which is zinc or zddp.
02-14-2020 03:52 PM
Gregory98zj no it will only pull codes.im was getting around 19 to 20 mpg.now about 15.
02-14-2020 03:17 PM
zjosh93
Quote:
Originally Posted by Gregory98zj View Post
magna flow. looking at the 2.25" Thunderbolt Catalytic Converter High Flow T409 Stainless Steel Rear O2 Nut
That's a ceramic matrix so it shouldn't trigger a catalyst code. In any case an O2 spacer almost always fixes it.

What zinc additive are you using? If you aren't burning much oil it shouldn't be poisoning your cats. Besides when a cat dies that way they typically just go cold not overheat. I'm just wondering if your getting into the too much zinc side of things.

Edit: If you want flow you can also just use a bigger cat. More flow area = less restriction. I put a 3" cat on my 93 and it blew through emissions here just fine.
02-14-2020 02:56 PM
Mr. Puddles Unless you are burning excessive amounts of oil Id say thats not it. What kind of mpg are you getting? Are you sure there is nothing in the exhaust and the pipe is not damaged?
02-14-2020 02:53 PM
Mr. Puddles
Quote:
Originally Posted by Gregory98zj View Post
ok just pulled codes with friends obd11.got nothing.i
Ok will that scanner pull live data or only codes?
02-14-2020 02:04 PM
Gregory98zj magna flow. looking at the 2.25" Thunderbolt Catalytic Converter High Flow T409 Stainless Steel Rear O2 Nut
02-14-2020 02:02 PM
Gregory98zj my motor has 65000 original miles on it app I use 0 that burn no oil between changes.i was looking at another type of cat than a magnaflow.
02-14-2020 02:00 PM
Gregory98zj ok just pulled codes with friends obd11.got nothing.i use 1 tbs for every quart, so that 7 tbs of zinc.
02-14-2020 01:52 PM
Mr. Puddles
Quote:
Originally Posted by jtec View Post
A 1998 zj 4.0l And you have a catalytic converter problem.
The Converter being red hot suggests there is excess fuel dumping into it, or less likely a seriously blocked exhaust.

A 1998 is a OBDII system, I would scan for codes, post ALL codes.
The cat is being damaged by a issue and you should correct the problem before it damages the new cat.
Tell us if you have access to a scanner to look at live data ECT, FUel trims, o2 sensor voltages.

This.
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