Lots of cold start engine noise after synthetic oil
Herp Derp Jerp

Joined: Nov 2011
Posts: 18,251
Likes: 17
From: Parham, ON
Year: 1999
Model: Cherokee
Engine: 4.0L OBD-II
80 PSI? Remove the oil pressure sending unit, clean out the galley, and test with a mechanical gauge. Either the galley's clogged or your sending unit is on its way out - when they get old or the connector becomes corroded they can read artificially high. 60 PSI at idle is way too high but I doubt it's legitimate.
My suggestion to run a 51515 is for two reasons:
1. Changing the oil filter - to ANYTHING else (except FRAM or similar cheap construction) will help you determine if the ABDV is bad.
2. If you're going to change it anyway, then considering the bucks you spent on Mobil 1, make the most out of your investment by running an oversized filter. Larger filters hold more contaminants and deliver better flow due to the increased surface area. Larger filters make an amazing difference in the winter.
My suggestion to run a 51515 is for two reasons:
1. Changing the oil filter - to ANYTHING else (except FRAM or similar cheap construction) will help you determine if the ABDV is bad.
2. If you're going to change it anyway, then considering the bucks you spent on Mobil 1, make the most out of your investment by running an oversized filter. Larger filters hold more contaminants and deliver better flow due to the increased surface area. Larger filters make an amazing difference in the winter.
Mobil 1 made my engine noisy... Since I switched to rotella t6 5w40 it's nice and calm
Did this with my bmw M3 as well she loves the rotella.

Did this with my bmw M3 as well she loves the rotella.
Seasoned Member
Joined: Nov 2013
Posts: 290
Likes: 1
From: USA
Year: 1995
Model: Grand Cherokee (ZJ)
Engine: 4.0L
2000' XJ Sport 4.0L AW4
95k miles
Hi, I recently changed my oil to the following oil:
Mobil 1 Full Synthetic 10w40
Wix filter
Every morning when I first crank it up, I get a lot of upper engine clatter which I did not get before the oil change. It goes away after a few seconds.
Temp approx. 65 degrees
Should I go with a thinner oil?
95k miles
Hi, I recently changed my oil to the following oil:
Mobil 1 Full Synthetic 10w40
Wix filter
Every morning when I first crank it up, I get a lot of upper engine clatter which I did not get before the oil change. It goes away after a few seconds.
Temp approx. 65 degrees
Should I go with a thinner oil?
Oil manufactures recommendations are usually based on the vehicle manufactures recommendations from the year(s) the vehicle was produced.
What to look for when switching to a lower viscosity oil or from a conventional oil to a synthetic ... is oil consumption and oil leaks.
I have used Mobile One 5-30w & 10-30w ext. perf. and also Mobile One 10-40w H.M.,. Haven't noticed any differences in engine noise while warming up or op temperatures.
I switch to a High Mileage oil every so often because it includes additives specifically for high mileage engines. It also has higher ZDDP.
I've been thinking of switching to a diesel engine oil such as Rotella
Last edited by Muddz; Oct 3, 2014 at 11:38 AM.
Seasoned Member
Joined: Jul 2010
Posts: 381
Likes: 0
From: Portland, OR
Year: 89
Model: Cherokee
Engine: 4.0 L
And why wouldnt you use MMO? Modern engine oils dont contain the proper amount of ZDDP to properly protect our 4.0 engines and theres no way i know of to add in that zddp. MMO is a mixture of detergents and friction modifiers that to me seems to clean, help prevent sludge, and reduce friction in my engine.
CF Veteran
Joined: Apr 2009
Posts: 4,734
Likes: 12
Year: 2015, 2012
Model: Grand Cherokee (WK2)
Engine: 3.6L
And why wouldnt you use MMO? Modern engine oils dont contain the proper amount of ZDDP to properly protect our 4.0 engines and theres no way i know of to add in that zddp. MMO is a mixture of detergents and friction modifiers that to me seems to clean, help prevent sludge, and reduce friction in my engine.
You must sell snake oil, too.
Last edited by Firestorm500; Sep 24, 2014 at 02:26 PM.
people use mmo to assemble engines because it will not run off the bearings. even after months. take that as you may. the only thing I put in the engine oil pan is engine oil.
Herp Derp Jerp

Joined: Nov 2011
Posts: 18,251
Likes: 17
From: Parham, ON
Year: 1999
Model: Cherokee
Engine: 4.0L OBD-II
Why would you? Is it free? It's never specified or required by anyone, ever. It's got some anecdotal uses but that's about it. You sound like a tobacco salesman before folks started figuring out smoking was bad for you. Why not, right?
That's a bit of a generalization. I can name plenty that have sufficient additives to support a 4.0L.
Well, you could, uh, buy one of those bottles of ZDDP... off the shelf... in stores... and then after that, pour it in to your engine...
Or don't play backyard chemist and just buy decent oil in the first place for the same price as ****ty oil...
Nah **** it. Got too much cash lying around here anyway. Damn stuff just blows out the window when it's windy!
Really? I've never heard that before. Can you please demonstrate the content of this wonderful magical product with a spectrographic analysis and laboratory tests? I'd love to see how MMO-treated oil performs on the API Sequence IIIG and IIIF tests.
Well, you could, uh, buy one of those bottles of ZDDP... off the shelf... in stores... and then after that, pour it in to your engine...
Or don't play backyard chemist and just buy decent oil in the first place for the same price as ****ty oil...
Nah **** it. Got too much cash lying around here anyway. Damn stuff just blows out the window when it's windy!
Really? I've never heard that before. Can you please demonstrate the content of this wonderful magical product with a spectrographic analysis and laboratory tests? I'd love to see how MMO-treated oil performs on the API Sequence IIIG and IIIF tests.
And why wouldnt you use MMO? Modern engine oils dont contain the proper amount of ZDDP to properly protect our 4.0 engines and theres no way i know of to add in that zddp. MMO is a mixture of detergents and friction modifiers that to me seems to clean, help prevent sludge, and reduce friction in my engine.
If you are worried about Zinc and Phosphorous, run one of the diesel oils like Rotella, or a boutique oil like Brad Penn. Or buy a ZDDP additive.
Sludge is a non-issue in (properly designed) engines built in the last 25 years unless you severely neglect maintenance, or they are so worn nothing seals up anymore, and modern motor oils do a fantastic job of reducing friction without being thinned out by additives.
Last edited by Radi; Sep 24, 2014 at 02:22 PM.



