switching to synthetic
Herp Derp Jerp

Joined: Nov 2011
Posts: 18,251
Likes: 17
From: Parham, ON
Year: 1999
Model: Cherokee
Engine: 4.0L OBD-II
CF Veteran
Joined: Sep 2010
Posts: 12,692
Likes: 6
From: Mercer County, NJ
Year: 2001
Model: Cherokee
Engine: 4.0L I6 HO
CF Veteran
Joined: Dec 2012
Posts: 4,169
Likes: 6
From: York, PA
Year: 1998
Model: Cherokee
Engine: 4.0
I ran Mobil 5000 for a few years before switching to Rotella T6. I never had a problem with it, but my vehicles are much happier with the T6!
CF Veteran
Joined: Apr 2009
Posts: 4,734
Likes: 12
Year: 2015, 2012
Model: Grand Cherokee (WK2)
Engine: 3.6L
CF Veteran
Joined: Apr 2009
Posts: 4,734
Likes: 12
Year: 2015, 2012
Model: Grand Cherokee (WK2)
Engine: 3.6L
CF Veteran
Joined: Dec 2012
Posts: 4,169
Likes: 6
From: York, PA
Year: 1998
Model: Cherokee
Engine: 4.0
They run much smoother and quieter. The 4.0 quieted down a lot and runs smooth as silk. The 2.2 in my daily driver has a condition where the hydraulic lash adjusters will tick heavily if the car's been sitting for 2 days or so while the oil drains out of the head. That issue is totally gone with the T6, and starts up and runs smooth with zero ticks. T6 5w40, FTW!
CF Veteran
Joined: Nov 2009
Posts: 8,172
Likes: 17
From: The Republic of TEXAS
Year: 1998
Model: Cherokee
Engine: 4.0L HO
.....might be worth something too since it is obsolete in engines built after 1930......but hey, a tractor motor is a tractor motor, right?.....so it should work fine.

I guess some folks just can't see the advantage of a 0W or a 5W oil flowing to the top of the motor (the valve train) quicker than 10W.


I guess some folks just can't see the advantage of a 0W or a 5W oil flowing to the top of the motor (the valve train) quicker than 10W.

Last edited by djb383; May 12, 2014 at 11:12 AM.
Seasoned Member
Joined: Jan 2013
Posts: 341
Likes: 1
From: Irvine Ca
Year: 1989 2 door
Model: Cherokee
Engine: 4.0
hey Salad which Rotella do you recommend for my 89 Renix 4.0 with 280k miles on it? Rotella 5 or 6? and what weight? i am in cali and its my daily driver
thanks
thanks
Herp Derp Jerp

Joined: Nov 2011
Posts: 18,251
Likes: 17
From: Parham, ON
Year: 1999
Model: Cherokee
Engine: 4.0L OBD-II
lol
Well ancient junk is all the same, apparently, even if the design never changed...
That's a very vague question. To answer it properly requires knowledge of your cooling system health, ambient temperature, driving habits, and vehicle history.
So use whatever grade your engine likes the most. Some engines don't like 40 weights. Go buy whatever you feel comfortable with and give it a go. Lighter oil is better for fuel economy, every time.
Remember to get a quality filter.
So use whatever grade your engine likes the most. Some engines don't like 40 weights. Go buy whatever you feel comfortable with and give it a go. Lighter oil is better for fuel economy, every time.
Remember to get a quality filter.
CF Veteran
Joined: Apr 2009
Posts: 4,734
Likes: 12
Year: 2015, 2012
Model: Grand Cherokee (WK2)
Engine: 3.6L
"Lighter oil is better for fuel economy, every time."
This stuff ends up being 30 or 40 weight by the time it approaches operating temperature. Oil spends very little time at the 5 or 10 weight. Any fuel economy savings would be unmeasurable in the average engine.
According to bobistheoilguy.com, even 0 weight oil is too heavy to immediately flow upon start-up.
This stuff ends up being 30 or 40 weight by the time it approaches operating temperature. Oil spends very little time at the 5 or 10 weight. Any fuel economy savings would be unmeasurable in the average engine.
According to bobistheoilguy.com, even 0 weight oil is too heavy to immediately flow upon start-up.
CF Veteran
Joined: Apr 2009
Posts: 4,734
Likes: 12
Year: 2015, 2012
Model: Grand Cherokee (WK2)
Engine: 3.6L
They run much smoother and quieter. The 4.0 quieted down a lot and runs smooth as silk. The 2.2 in my daily driver has a condition where the hydraulic lash adjusters will tick heavily if the car's been sitting for 2 days or so while the oil drains out of the head. That issue is totally gone with the T6, and starts up and runs smooth with zero ticks. T6 5w40, FTW!
CF Veteran
Joined: Nov 2009
Posts: 8,172
Likes: 17
From: The Republic of TEXAS
Year: 1998
Model: Cherokee
Engine: 4.0L HO
"Lighter oil is better for fuel economy, every time."
This stuff ends up being 30 or 40 weight by the time it approaches operating temperature. Oil spends very little time at the 5 or 10 weight. Any fuel economy savings would be unmeasurable in the average engine.
According to bobistheoilguy.com, even 0 weight oil is too heavy to immediately flow upon start-up.
This stuff ends up being 30 or 40 weight by the time it approaches operating temperature. Oil spends very little time at the 5 or 10 weight. Any fuel economy savings would be unmeasurable in the average engine.
According to bobistheoilguy.com, even 0 weight oil is too heavy to immediately flow upon start-up.
CF Veteran
Joined: Sep 2010
Posts: 12,692
Likes: 6
From: Mercer County, NJ
Year: 2001
Model: Cherokee
Engine: 4.0L I6 HO
According to that link earlier its true, although they have a lower starting viscosity its still too much for qn engine. But the 30 weights all become a viscosity of 10 at normal operating temperature. That link was the best thing ive read in a while
Thread Starter
Junior Member
Joined: Apr 2014
Posts: 74
Likes: 1
Year: 2000
Model: Cherokee
Engine: 4.0
Update: so like you all know I switched to synthetic a few days ago, all was well until this morning......it was about 30° outside this morning when I went to start her up. Immediately I noticed piston slap, very lightly but it was there. Almost sounded like a really quiet diesel engine. After it warmed up it went away. I will probably be switching back to dyno oil here shortly. Anyone use castrol gtx? Im really hesitant to use an oil made for diesel engines (rotella).
CF Veteran
Joined: Feb 2013
Posts: 1,802
Likes: 2
From: Justin, TEXAS
Year: 1988
Model: Cherokee
Engine: 4.0
Update: so like you all know I switched to synthetic a few days ago, all was well until this morning......it was about 30° outside this morning when I went to start her up. Immediately I noticed piston slap, very lightly but it was there. Almost sounded like a really quiet diesel engine. After it warmed up it went away. I will probably be switching back to dyno oil here shortly. Anyone use castrol gtx? Im really hesitant to use an oil made for diesel engines (rotella).
Pair it with a Napa gold filter and it's awesome



