Which oil?

Jeepcrush4 · Oct 8, 2009

I just bought a 1997 cherokee 4.0 and was in the process if doing an oil change. The engine was rebuilt by the second previous owner and was a liitle over 100k miles. I understand the idea of synthetic oil loosening gunk and varnish possibly causing blockage, but I've always had success with valvoline 10w30 synthetic. I've read that some experienced issues on going synthetic with high mile 4.0 engines. Some recommended havoline 10w40 while others said generic. I'll go with the consensus. Avoid synthetic? Any particular brand and weight? No oil leaks thus far.

Slip Kid · Oct 8, 2009

I never had any leaks and I used Syntec for quite a while, starting at 200k. That is, no NEW leaks

Jeepcrush4 · Oct 8, 2009

Thats a relief, so far

tomhil · Oct 8, 2009

I would say if the engine is in good shape with no leaks, synthetic should be fine. A lot of people on here like to run sell oil, but for high mileage I like castol gtx.

MG_43 · Oct 8, 2009

When I bought my 92 4.0 it had 183K on it, I switched to mobil 1 and have not had any problems. It now has 202K and runs like a new one. Just don't use (yellow death) Pens oil which contains candle wax or Frahm filters (absolute junk). The choice is up to you.

Johnnie Walker · Oct 8, 2009

Full syn is not necessary, but if you want to go for it. I would recommend at least a synthetic blend. I've been running the Valvoline max life syn. blend and its working out well. In most other vehicles I have run Amsoil full syn., and probably will run it again in my XJ soon. My top 3 full syn.s are.. Amsoil, Pennzoil Platinum (only pennz/ product I will ever use, the rest are garbage. And the Valvoline Synpower. These 3 have ZDDP in them (Zinc, for those that don't know) which helps keep cast iron blocks strong.
As far as oil filters go, I recommend Wix/Napa Gold filters (made by Wix, usually cheaper), Bosch, Amsoil filters are great as well.

wim hoppenbrouwers · Oct 8, 2009

Johnnie Walker said:
Full syn is not necessary, but if you want to go for it. I would recommend at least a synthetic blend. I've been running the Valvoline max life syn. blend and its working out well. In most other vehicles I have run Amsoil full syn., and probably will run it again in my XJ soon. My top 3 full syn.s are.. Amsoil, Pennzoil Platinum (only pennz/ product I will ever use, the rest are garbage. And the Valvoline Synpower. These 3 have ZDDP in them (Zinc, for those that don't know) which helps keep cast iron blocks strong.
As far as oil filters go, I recommend Wix/Napa Gold filters (made by Wix, usually cheaper), Bosch, Amsoil filters are great as well.

Quote:These 3 have ZDDP in them (Zinc, for those that don't know) which helps keep cast iron blocks strong.

Hallo. How can you know that? Is there a SL Mark on the oilcan?
I use 10W40 halfsynt.

wim

Johnnie Walker · Oct 8, 2009

I have searched on the wonderful interweb about it.

winterbeater · Oct 8, 2009

Obvious comment. Oh no, not another oil thread! Please search.

And ZDDP os for flat tappet wear more than anything.

stephenspann27 · Oct 8, 2009

Johnnie Walker said:
Full syn is not necessary, but if you want to go for it. I would recommend at least a synthetic blend. I've been running the Valvoline max life syn. blend and its working out well. In most other vehicles I have run Amsoil full syn., and probably will run it again in my XJ soon. My top 3 full syn.s are.. Amsoil, Pennzoil Platinum (only pennz/ product I will ever use, the rest are garbage. And the Valvoline Synpower. These 3 have ZDDP in them (Zinc, for those that don't know) which helps keep cast iron blocks strong.
As far as oil filters go, I recommend Wix/Napa Gold filters (made by Wix, usually cheaper), Bosch, Amsoil filters are great as well.

The "synthetic blends" usually have something like 5% synthetic parts. I read a bunch about it a while back. They take a dino oil that they normally sell for say.. $4 a quart, add 5% synthetic to it, and charge $5.50 for it. Its marketing.. they make their biggest profit on "synthetic blend." Mobile 1 tried to stay out of that game.. but even they are now offering a synthetic blend.

joe_peters · Oct 8, 2009

winterbeater said:
Obvious comment. Oh no, not another oil thread! Please search.

And ZDDP os for flat tappet wear more than anything.

x2, ZDDP prevents premature wearing of the tappet/camshaft. I love my Rotella T 10W30 Dino. I would use Rotella synthetic but can't justify the cost considering I change oil every 3 months instead of on mileage.

89xj · Oct 8, 2009

ive used rotella T and rotella syn in my 89 for the past 6 years.

Jeepcrush4 · Oct 8, 2009

I went and used valvoline full synthetic and it runs smooth. So far so good.

Jeepcrush4 · Oct 8, 2009

Btw, what is a ZDDP?

kastein · Oct 8, 2009

zinc (something something) phosphate I believe. It's an additive that helps out with valve tappets and tends to preserve iron block engines better - or so I understand.

EDIT: Zinc Dialkyl-Dithio Phosphate. The EPA does not like it, engines do.

http://www.macysgarage.com/myweb6/ZDDP.htm

winterbeater · Oct 8, 2009

kastein said:
zinc (something something) phosphate I believe. It's an additive that helps out with valve tappets and tends to preserve iron block engines better - or so I understand.

EDIT: Zinc Dialkyl-Dithio Phosphate. The EPA does not like it, engines do.

Supposedly catalytic converters don't either.

kastein · Oct 8, 2009

yeah, was just reading that... I'll take a working engine and a screwed catalytic converter that needs replacement over the reverse!

yamahadrummer · Oct 8, 2009

When i got my XJ it had 82,000mi on it, and I don't know what was used for oil before I bought it. I used Quaker State 4x4 full synthetic 10w30 for the first oil change, as I had used Quaker State for my two vehicles I owned before the Jeep. A friend of mine who is an auto tech swore Quaker was crap and told me to used Valvoline, so since then I have used Valvoline synpower, switching between 10w30 when it is warm, 5w30 when it's winter (here in Nebraska we have heat and cold extremes, I find the Jeep starts easier and warms up a bit faster with 5w30, as most of you im sure know). I have never had a problem, runs smooth as silk. got 103,000mi now, two years later. I change change every 3000mi.

winterbeater said:
Supposedly catalytic converters don't either.

well good thing I don't have one of those!

Jeepcrush4 · Oct 9, 2009

Very cool. I've always run valvoline in all my cars. I had it in my z28 and beat the piss out if it and had no wear whatsoever.

X-defector · Oct 9, 2009

I (and all of us) have read a bunch about ZDDP and how it helps protect flat tappet lifters and cams. The science is pretty simple.

My inquiring mind wants to know, why exactly is it that newer-grade oils cannot effectively protect flat tappet lifters and cams? That's something no one has ever really talked about. Is it because the lifter/cam movement completely shears the oil barrier between the two? In a well-worn engine, a complete shearing like that seems improbable....especially on every single cam rotation (otherwise we'd have old XJs and TJs lying dead all over roads everywhere). Or is it another reason? Or is it really just internet wisdom and paranoia?

The new oil tests are brutal, and even the previous oil grades would fail pretty badly in some of them. I'm not sure why they wouldn't be able to protect a standard-service flat tappet engine pretty effectively, but then maybe I'm missing something. :anon:

Which oil?

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