87 yj jeep wrangler IL6 4.2l stick: oil preference
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An engine could run excessively rich if the oxygen sensor has failed. Back in 1987, most electronic controls could only give you an error code if the O2S had a short circuit, open circuit, or a voltage that is completely out of range. A failing O2 sensor might cause the engine to run excessively rich, quickly fouling the spark plugs and destroying the cat. An incorrect air/fuel mixture can also cause misfire.
The other problem is that 1980s carburetors and smog devices failed regularly. Having a maze of vacuum hoses makes diagnosis even more challenging to diagnose. How does the choke work? If the choke will not open at the proper temperature, it will cause an extra rich air/fuel mixture.
As for the oil, I'm not sure 10w30 or 5w30 is totally the problem. Just think of what 10w30 and 5w30 was like in the 1980s. Some of those engines took 10w40, so I recommend finding a Haynes book about 1980s Jeeps. It would tell you what oil viscosity you need, and possibly help you diagnose a poor running engine.
There is another challenge with carb engines. Back when those cars were built, ethanol based fuels were less common.
The other problem is that 1980s carburetors and smog devices failed regularly. Having a maze of vacuum hoses makes diagnosis even more challenging to diagnose. How does the choke work? If the choke will not open at the proper temperature, it will cause an extra rich air/fuel mixture.
As for the oil, I'm not sure 10w30 or 5w30 is totally the problem. Just think of what 10w30 and 5w30 was like in the 1980s. Some of those engines took 10w40, so I recommend finding a Haynes book about 1980s Jeeps. It would tell you what oil viscosity you need, and possibly help you diagnose a poor running engine.
There is another challenge with carb engines. Back when those cars were built, ethanol based fuels were less common.
Originally Posted By: JoPeter
....
At same viscosity, I am advised synthetic do not have "shear" capabilities like conventional ones or diesel oils.
Please correct if I am wrong?
If iam wrong, then I dont need to worry about conventional & I can just goes with my eyes closed to synthetic on my oldie which has more OCI?
Synthetics are generally superior(but the gap has closed dramatically in the last few years), and at operating temperature will be the same thickness as a conventional oil. In your case he only down side to using them is that in older vehicles you may see some seepage or leakage around seals.
In that engine I would use a solid 10w40 if you can find it. Rotella synthetic 5w40 would be an excellent choice if you decide to use synthetic. But if you are just driving in the summer, the 15w40 diesel oil would probably work well for you, since all your startups will be above 10-15C.
Lifter noise: on the Jeep 4.0, M1 is known to make more noise and show a lot of Iron in UOAs. IIRC the 4.0 was based on the 4.2, so there may be the same effect on yours.
You said that the Jeep is backfiring and running roughly. You did NOT mention that you had replaced the spark plugs, cap and rotor. If you still haven't I would most definitely do that as the first step.
....
At same viscosity, I am advised synthetic do not have "shear" capabilities like conventional ones or diesel oils.
Please correct if I am wrong?
If iam wrong, then I dont need to worry about conventional & I can just goes with my eyes closed to synthetic on my oldie which has more OCI?
Synthetics are generally superior(but the gap has closed dramatically in the last few years), and at operating temperature will be the same thickness as a conventional oil. In your case he only down side to using them is that in older vehicles you may see some seepage or leakage around seals.
In that engine I would use a solid 10w40 if you can find it. Rotella synthetic 5w40 would be an excellent choice if you decide to use synthetic. But if you are just driving in the summer, the 15w40 diesel oil would probably work well for you, since all your startups will be above 10-15C.
Lifter noise: on the Jeep 4.0, M1 is known to make more noise and show a lot of Iron in UOAs. IIRC the 4.0 was based on the 4.2, so there may be the same effect on yours.
You said that the Jeep is backfiring and running roughly. You did NOT mention that you had replaced the spark plugs, cap and rotor. If you still haven't I would most definitely do that as the first step.
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Synthetics are generally superior(but the gap has closed dramatically in the last few years), .....older vehicles you may see some seepage or leakage around seals.
This is what majority of folks advised me.
In that engine I would use a solid 10w40 if you can find it. Rotella synthetic 5w40 would be an excellent choice if you decide to use synthetic. But if you are just driving in the summer, the 15w40 diesel oil would probably work well for you, since all your startups will be above 10-15C...
Will using a synthetic diesel for winter & colder months (like 5w40..heard from many as good for cold starts when in NY temp goes way low like this winter), then changing to non synthetic diesel oil like Rotella 15 w 40 for warmer months will be a problem? or just stick to either non synthetic diesel all season or synthetic all season. Please advice?
You said that the Jeep is backfiring and running roughly. You did NOT mention that you had replaced the spark plugs, cap and rotor. If you still haven't I would most definitely do that as the first step.[/quote]
Thanks all for your support. Was at the mechanic today. Jeep runs fine now. They figured out it was due to intermittent flow of charge to distributor due to faulty wiring.
@ Kuato: I changed spark plugs ( many times as they got black in a few hours )distributor & cap,ignition coil and module since these symptoms started. But finding faulty wiring was beyond my skills. I doubted like the previous 2 mechanics on motor and module and weber carb.
In that engine I would use a solid 10w40 if you can find it. Rotella synthetic 5w40 would be an excellent choice if you decide to use synthetic. But if you are just driving in the summer, the 15w40 diesel oil would probably work well for you, since all your startups will be above 10-15C...
Will using a synthetic diesel for winter & colder months (like 5w40..heard from many as good for cold starts when in NY temp goes way low like this winter), then changing to non synthetic diesel oil like Rotella 15 w 40 for warmer months will be a problem? or just stick to either non synthetic diesel all season or synthetic all season. Please advice?
You said that the Jeep is backfiring and running roughly. You did NOT mention that you had replaced the spark plugs, cap and rotor. If you still haven't I would most definitely do that as the first step.[/quote]
Thanks all for your support. Was at the mechanic today. Jeep runs fine now. They figured out it was due to intermittent flow of charge to distributor due to faulty wiring.
@ Kuato: I changed spark plugs ( many times as they got black in a few hours )distributor & cap,ignition coil and module since these symptoms started. But finding faulty wiring was beyond my skills. I doubted like the previous 2 mechanics on motor and module and weber carb.
Originally Posted By: artificialist
An engine could run excessively rich if the oxygen sensor has failed. Back in 1987, most electronic controls could only give you an error code if the O2S had a short circuit, open circuit, or a voltage that is completely out of range. A failing O2 sensor might cause the engine to run excessively rich, quickly fouling the spark plugs and destroying the cat. An incorrect air/fuel mixture can also cause misfire.
The other problem is that 1980s carburetors and smog devices failed regularly. Having a maze of vacuum hoses makes diagnosis even more challenging to diagnose. How does the choke work? If the choke will not open at the proper temperature, it will cause an extra rich air/fuel mixture.
As for the oil, I'm not sure 10w30 or 5w30 is totally the problem. Just think of what 10w30 and 5w30 was like in the 1980s. Some of those engines took 10w40, so I recommend finding a Haynes book about 1980s Jeeps. It would tell you what oil viscosity you need, and possibly help you diagnose a poor running engine.
There is another challenge with carb engines. Back when those cars were built, ethanol based fuels were less common.
Thanks artificialist. Nice pointer about O2 sensor. I dont know when was the last time O2 sensor was replaced on this jeep, since I have this only from nov 14. Since mechanic found the cause of misfiring (to intermittent flow of charge to distributor due to faulty wiring.) Jeep runs fine now. I have to ask in Jeep forum about replacement of O2 sensor. Haynes 6-15 says..." Checking the o2s is beyond the scope of the home mechanic. Take the vehicle to dealer". I am scared of the word "dealer" and will try to get info from these forums.
Also not sure weber carb has an o2s. i am sure stock Carter BBD carb has o2s.
Oil part.. i am going to go w Rotella 15w 40 in summer. come winter i will go 5 w 40.
An engine could run excessively rich if the oxygen sensor has failed. Back in 1987, most electronic controls could only give you an error code if the O2S had a short circuit, open circuit, or a voltage that is completely out of range. A failing O2 sensor might cause the engine to run excessively rich, quickly fouling the spark plugs and destroying the cat. An incorrect air/fuel mixture can also cause misfire.
The other problem is that 1980s carburetors and smog devices failed regularly. Having a maze of vacuum hoses makes diagnosis even more challenging to diagnose. How does the choke work? If the choke will not open at the proper temperature, it will cause an extra rich air/fuel mixture.
As for the oil, I'm not sure 10w30 or 5w30 is totally the problem. Just think of what 10w30 and 5w30 was like in the 1980s. Some of those engines took 10w40, so I recommend finding a Haynes book about 1980s Jeeps. It would tell you what oil viscosity you need, and possibly help you diagnose a poor running engine.
There is another challenge with carb engines. Back when those cars were built, ethanol based fuels were less common.
Thanks artificialist. Nice pointer about O2 sensor. I dont know when was the last time O2 sensor was replaced on this jeep, since I have this only from nov 14. Since mechanic found the cause of misfiring (to intermittent flow of charge to distributor due to faulty wiring.) Jeep runs fine now. I have to ask in Jeep forum about replacement of O2 sensor. Haynes 6-15 says..." Checking the o2s is beyond the scope of the home mechanic. Take the vehicle to dealer". I am scared of the word "dealer" and will try to get info from these forums.
Also not sure weber carb has an o2s. i am sure stock Carter BBD carb has o2s.
Oil part.. i am going to go w Rotella 15w 40 in summer. come winter i will go 5 w 40.
Originally Posted By: artificialist
The other problem is that 1980s carburetors and smog devices failed regularly. Having a maze of vacuum hoses makes diagnosis even more challenging to diagnose. How does the choke work? If the choke will not open at the proper temperature, it will cause an extra rich air/fuel mixture.
PO installed Weber. So he took off all those vacuum hoses associated with the stock carter carb.
Since the hickup and misfiring started in winter I might have to check choke again in next winter carefully as now its warm enough w/o choke
As for the oil, I'm not sure 10w30 or 5w30 is totally the problem....
Absolutely correct. I just have to use the right viscous in this old engine.
The other problem is that 1980s carburetors and smog devices failed regularly. Having a maze of vacuum hoses makes diagnosis even more challenging to diagnose. How does the choke work? If the choke will not open at the proper temperature, it will cause an extra rich air/fuel mixture.
PO installed Weber. So he took off all those vacuum hoses associated with the stock carter carb.
Since the hickup and misfiring started in winter I might have to check choke again in next winter carefully as now its warm enough w/o choke
As for the oil, I'm not sure 10w30 or 5w30 is totally the problem....
Absolutely correct. I just have to use the right viscous in this old engine.
Originally Posted By: Dyusik
Mo the bad head was early 2k 4.0, and most jeeps I see run sale oil to 300k+.
Here is food for thought,10w30 is thicker only at colder temps, and is usually 1cst thinner than 5w30 @ 100celsius.
If you want add pack delo is the way to go with boron out the ahem. I never buy into the whole oil ruined my engine stuff, because there are a lot of people running 30 40 wts with lucas hdos thickening it to beyond 60 and 70 wt oils. Cars dont blow up, just become sluggish and sooper quiet
Thanks for the specifics....
totally agree with oil ruined engine comment.
1) What u mean : "most jeeps I see run sale oil to 300k+." and ..."add pack delo is the way to go with boron out the ahem."
Mo the bad head was early 2k 4.0, and most jeeps I see run sale oil to 300k+.
Here is food for thought,10w30 is thicker only at colder temps, and is usually 1cst thinner than 5w30 @ 100celsius.
If you want add pack delo is the way to go with boron out the ahem. I never buy into the whole oil ruined my engine stuff, because there are a lot of people running 30 40 wts with lucas hdos thickening it to beyond 60 and 70 wt oils. Cars dont blow up, just become sluggish and sooper quiet
Thanks for the specifics....
totally agree with oil ruined engine comment.
1) What u mean : "most jeeps I see run sale oil to 300k+." and ..."add pack delo is the way to go with boron out the ahem."
Originally Posted By: crazyoildude
joseph Did you do a compression test you could have a piston problem or maybe you broke a rocker arm/stud or a valve spring that could cause a bad missfire also. Take the valve cover off and look to see if they are all intact then start it and watch them and see if they are all doing the same thing at different times of course
compression test done by mechanic:
1. 90
2. 115
3. 90
4. 125
5.125
6.125
He said as jeep is not misfiring or anything let it run and will check again after a few weeks.
Thanks
joseph Did you do a compression test you could have a piston problem or maybe you broke a rocker arm/stud or a valve spring that could cause a bad missfire also. Take the valve cover off and look to see if they are all intact then start it and watch them and see if they are all doing the same thing at different times of course
compression test done by mechanic:
1. 90
2. 115
3. 90
4. 125
5.125
6.125
He said as jeep is not misfiring or anything let it run and will check again after a few weeks.
Thanks
Originally Posted By: JoPeter
Oil part.. i am going to go w Rotella 15w 40 in summer. come winter i will go 5 w 40.
That may work for you but is overkill on the thick side IMO even though these engines like thick. Have you considered Rotella 10w30 instead? Would be my suggestion...
Oil part.. i am going to go w Rotella 15w 40 in summer. come winter i will go 5 w 40.
That may work for you but is overkill on the thick side IMO even though these engines like thick. Have you considered Rotella 10w30 instead? Would be my suggestion...
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