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synthetic oil on higher milage engine??

93xj-jeeper

NAXJA Forum User
I have searched for this quite a bit but just did not quite find what i was looking for.

my 93 xj has 120,000 and has always ran regular oil. I have been reading lately about all the advantages to synthetic oil and was wondering if it would be ok to switch to it with this many miles.

The thing is, i just got done about a week ago with some engine work. i had my valves redone and therefore replaced the headgasket and the valve cover gasket. Where do the leaks that are generally "caused" by swithching to synthetic oil come from?

Also, if the switch was ok would i want to use full synthetic or blend. i would use mobile 1 for sure by the way.

Please let me know what you guys think about this, because like i said just got done working on engine, so i dont want any more leaks, but would like the advantages of synthetic.
 
i like quaker state synthetic and run it in my jeeps and my avalanche.

i use 10-40 in my jeeps and 10-30 in the lanche.

synthetics clean the motor of any buildup. they "cause" leaks by removing any buildup on the gaskets that may be stopping up a leak.

4.0's leak from a few places. rear main seal, valve cover gasket, oil filter adapter gasket, and oil pan gasket.

if you run a synthetic in a higher mileage engine, run a heavier oil, especially in the summer when its hot.
 
ok thanks for your reply. by the way guys sorry for posting in this forum, i know it is the wrong one for this thread and did not realize i was in it at the time.

so, basically im trying to find out if the synthetic oil will cause these leaks with that many miles on there and never running it before. is it worth the risk for the switch over, and do i want to run full or blend?? i cant decide if i should do this or not. thanks.
 
93xj-jeeper said:
ok thanks for your reply. by the way guys sorry for posting in this forum, i know it is the wrong one for this thread and did not realize i was in it at the time.

so, basically im trying to find out if the synthetic oil will cause these leaks with that many miles on there and never running it before. is it worth the risk for the switch over, and do i want to run full or blend?? i cant decide if i should do this or not. thanks.

i have a 94 with about 115,000 miles in it. I just switched to synthetic, Mobil 1 and have a very small leak. When I park it in the garage i get a drop of oil from leaving it there overnight. The amount of oil that is leaking hasn't given me enough concern to find where the leak is. But it does seem like it runs smoother. I live in North Pole, AK, and I did the switch when it was -50 degrees since the normal oil sucks here in those temps. Side note, my xj was left on the entire day when it the temp was hovering around -50, or it would be a very rough start, even with the block heater and a heater blower in the engine compartment.
 
ok thanks for your post asjackman,

anyone else have similiar issues in warmer climates. anybody switch over at a similiar milage and have leaks, if so where.

Thanks, all suggestions and information is welcome.
 
I have a 94' with 167k on the odo... I switched to Royal Purple about 3-4 months ago. had a rear main leak before, hasn't gotten any worse with the RP. its a full synth which I also have in both diffs, and I just got the max ATF for my t-case. I am in southern CA. wheeled Johnson Valley in Dec and just recently Stoddard Valley @ about 80ºF. I drive hard on the street and I don't work on my own jeep very much so it goes a bit between oil changes.
 
with 175,000 i switched to 10w 30 Red Line Oil

great stuff

free synthetic? how can i pass that up?
 
any other opinions? the main thing i am worried about is the rear main seal.

do you guys think that synthetic is really that much better and worth it for me to switch.

if not what do you think i should use as far as conventional. ive been using valvoline with a fram filter lately but would like to switch it up because of the fram (i am having low oil pressure and thinking maybe its from that?)

would castrol gtx with k&n filter be a pretty good choice. and does mobile 1 make a conventional oil because i was looking today and saw a "mobile 1 clean 5000" which seems to be just a conventional but does it have a lot of clean additives that would possibly remove deposits around seals, which in that case i might as well switch to the synthetic then.

thanks, sorry for all the posts so fast, im just trying to figure out what to do and could really use some help as i need an oil change pretty soon!
 
Castrol GTX is one of the best conventional oils....Mobil 1 is a very good synthetic...I gained 6 HP when I changed from 20-50 GTX to 5-30 Mobil 1 in my dragbike...piston/ring, cam/follower wear became a thing of the past also. the downside was slightly increased wear on the tranny gears...it was a good trade-off though....the trans needs frequent refreshing due to impact loading regardless of lube type.

I would be very careful changing from mineral oil to synthetic in applications where there are roller/needle bearings/gears etc. the synth has poor impact protection. One of the major motorcycle racing crankshaft builders refers to a major synthetic oil as purple death.
 
I tried full synthetic at 240,000. I didn't experience any leaks, but I did start hearing piston slap alot more. I put blend back in and the noise went away. I think the full synthetic was too slick.
 
I'm using Amsoil and had no new problems at all when I switched over at 130,000 miles. The rear main seems to be a leaking a little bit, but that's not anything new.

Robert
 
We bought two TJ's last year, both were in the 100K mile range, both were switched to Mobil-1 10w30 'green cap' and Mobil-1 M-204 filters within a week of getting them, neither one leaked or has devleoped leaks. My 98XJ has over 250,000mi on it and has been running Mobil-1 since new.
Ran it in my 1981 Yamaha XS1100LH and had to change it back out, it was too slippery and the clutch would not work [wet clutch]. Switched to Castrol syntec and things worked fine.
Have considered Royal Purple, Redline but no body in my area carries them in stock so to me thats not an option.
 
allright guys thanks for your replys. i think i will go ahead and switch then.

just out of curiousity, would it do any good to switch to a blend first then to the full synthetic.

i thought about it and figured proably not because once i did switch to the mobile 1 full it would probably clean away the rest of the deposits anyways, is that what you would say rich p or anyone? just checking if it would be better as a more gradual approach?
 
93xj-jeeper said:
any leaks xj ranger?

none that werent there before...
 
I've a '90 and been trying to decide on this as well. It's got 174000km on it now, although I don't know exactly how accurate that is as it was km, then a mph gauge as it was in the US a spell and back to km now back in Canada.

I put something in with the oil to help clean things, and I've noticed a big difference with it in the last day or two since doing it. I'm not sure how using a pure syn will work in mine, as I'm a bit leary as I've been dealing with oil leaks. The valve cover has been redone, the grommet/ccv replaced as well as a new oil cap. Just the breather hose hasn't been replaced as of yet, but looking at doing that as well. [the two aforementioned were leaking oil from after getting the valve cover done]
I can get hold of valvoline blend here which I've been comtimplating as I really need to do an oil change and is supposedly for engines over 120000. I want the benefit of the detergents of the syn, with out having to worry too much about getting a major leak in the rear main or such. Is this a good way to go? Should I use the valvoline in a 10-40? stick with 10-30? or just stick with dino and put in a detergent to keep things clean myself like I just did? I'm basically wanting to treat my engine with kid gloves as I don't know what exactly has been done in it internally over the last few years until I got it, and before that, a little old man owned it, so it was never driven hard before about 4 or 5 years before now, and has sat for 3 years until it becamse mine.
When changing the grommet out, I tried to get out as much buildup as I could in there, as well as the breather tube. Pretty gunky unfortuately. Maybe a stupid quesion, but is there anything I should put in to help do a 'quick clean' before changing the oil and filter as well? I'd like to get as much crap out of it, and cleaned up as possible.

thanks for any adivce
 
Won't make that much difference, what will need to be watched is the color of the oil in the dipstick, once you can't read the marks thru the oil anymore change the filter...for that I would use cheaper filters, purolator, wix, etc, at least for the first 3 or so oil changes. No use in burning up a $12 filter thats going to be changed out in 1500mi or less. Depends on how dirty the engine is.
 
cykaaro said:
I've a '90 and been trying to decide on this as well. It's got 174000km on it now, although I don't know exactly how accurate that is as it was km, then a mph gauge as it was in the US a spell and back to km now back in Canada.
When changing the grommet out, I tried to get out as much buildup as I could in there, as well as the breather tube. Pretty gunky unfortuately. Maybe a stupid quesion, but is there anything I should put in to help do a 'quick clean' before changing the oil and filter as well? I'd like to get as much crap out of it, and cleaned up as possible.

thanks for any adivce

I would not bother trying to clean the tubing out, just put new stuff on. I guess you could soak it in a good degreaser and go at them with pipe cleaners or a coathanger but unless you are attached to them for sentimental reasons I'd just replace them. :laugh3:
 
RichP said:
I would not bother trying to clean the tubing out, just put new stuff on. I guess you could soak it in a good degreaser and go at them with pipe cleaners or a coathanger but unless you are attached to them for sentimental reasons I'd just replace them. :laugh3:

Na, I'm not that anal about my tubing :laugh3: I kept the old one as it didn't seem that old and just keep it 'just in case', but the tubing on it is actually fine. Easy to clean it out, but the grommet was leaking so since they sell only together, for the sake of $12 I replaced both grommet and tube. Oil cap got changed to a new one this morning. The breather tube is the last one to do. Not sure what that's going to run, as it seems like one big assembly. Afraid of how much that will cost, but were the grommet part of it goes into the valve cover, is a bit loose fitting so leaks a wee bit, but probably more now that the other two have been replaced I would think. Overall the engine is running a hell of a lot smoother. Oil has been put in on a regular basis since I was loosing too much. Filter is the infamous FRAM but will be changed out very soon, but to what I'm not sure. Seems that mainly fram and quaker are available here. There is K&N but don't know which one fits. I'm also running with Lucas oil stabilizer, and just put in the oil cleaning treatment. even since I put the treatment in two days ago, I can notice the difference.
When I put in the new grommet, I took a large flat screwdriver and carefully scraped out as much of the gunk in there as I could. Did the breather tube as well. Less crap sitting in there I figured the better. Just had the valve cover done so not about ot rip it off until I need to.
With doing an oil change in the coming weeks, just want to make the right decision of what to use. My dealership wants to do one and inspection for $40, but thinking of doing the oil change myself. Doesn't seem terribly difficult, and all I need is the wrench and catch basin for the drained oil. MIght as well save the $$ for other things I need to get doen.
 
I have changed to synthetic at the following mileages with the listed results. Always Mobile1 Full Synth.

98 VW GTI VR6 at 26k miles - no leaks, now at 70k miles, still no leaks
96 VW GTI VR6 at 65k miles - small leak iirc
89 Jeep Cherokee at 118k - Rear Main seal leak
99 Rover Disco II at 70k - leak developed

I'm 3 out of 4 for getting leaks within 3-5k miles of switching to full synthetic. Many people will argue that it was caused by other things and some people change in high mile engines without problems. I, however will never change to synthetic in a vehicle with high miles again. I've ruined too many driveways and wasted too much on refilling that expensive synthetic oil.
 
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