7500-mile Oil Changes??? Normal Compression??

[HobbyWrench]

I decided to take a look at a '93 Legacy L sedan, EJ22, NA, 5MT, FWD, w/135k miles, that was for sale (to start adding to my Legacy collection).

Looking under the hood, and talking with the owner to gauge the maintenance schedule, his reply my oil-change-frequency question was '7500 miles, according to the manual.' (I think there obviously was a misinterpretation of the manual.)

The owner claimed to regularly check the oil level. (I'm assuming this means adding as necessary - and not just monitoring it as it went down!)

(Admittedly, I did NOT ask what weight oil was used, but I'm assuming 5w-30, as is generally recommended in the manuals.)

Because the car seems to generally in good shape, I thought I'd do a compression check to gauge engine damage as a result.

With fuel pump wire pulled, throttle opened, and 3-5 second cranking over per cylinder check, each cylinder registered 180psi compression with a screw-in tester. (Is this the correct procedure?)

With this (apparent) high compression, should I be concerned about potential engine damage? The engine seemed to run nicely, accelerating well with the 5MT, with no smoking from the exhaust.

In light of these compression readings, should I give this car any further consideration, or I should not walk, BUT RUN IN THE OPPOSITE DIRECTION?!

I'd appreciate your opinion! Thanks.

Mike


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'90 Legacy LS Wagon, EJ22, NA, 4EAT, FWD w/194K+ miles

[scuzzy]

I decided to take a look at a '93 Legacy L sedan, EJ22, NA, 5MT, FWD, w/135k miles, that was for sale (to start adding to my Legacy collection).

Looking under the hood, and talking with the owner to gauge the maintenance schedule, his reply my oil-change-frequency question was '7500 miles, according to the manual.' (I think there obviously was a misinterpretation of the manual.)

The owner claimed to regularly check the oil level. (I'm assuming this means adding as necessary - and not just monitoring it as it went down!)

(Admittedly, I did NOT ask what weight oil was used, but I'm assuming 5w-30, as is generally recommended in the manuals.)

Because the car seems to generally in good shape, I thought I'd do a compression check to gauge engine damage as a result.

With fuel pump wire pulled, throttle opened, and 3-5 second cranking over per cylinder check, each cylinder registered 180lbs pressure with a screw-in tester. (Is this the correct procedure?)

With this (apparent) high compression, should I be concerned about potential engine damage? The engine seemed to run nicely, accelerating well with the 5MT, with no smoking from the exhaust.

In light of these compression readings, should I give this car any further consideration, or I should not walk, BUT RUN IN THE OPPOSITE DIRECTION?!

I'd appreciate your opinion! Thanks.

Mike

As long as the numbers are within 10% of each other (so if cylinder 1 checks in at 180psi, then cylinders 2-4 should read between 162 and 198 at absolute most) then the engine is fine.
180 is probably normal for a NA engine, my turbo engine runs 150psi and is 8.0:1 CR versus 9.5:1 of a NA (IIRC)

[Psychoreo]

those numbers for compression sound about right.
as for the oil change rituals, i thought i remembered it saying some number that seemed a bit high in my owners manual as well. As long as he used the right weight oil and didn't drive it really hard or overheat it (find out if it's been overheated,) should be a good car.

[HobbyWrench]

Thanks for both of your comments.

I did ask if it had overheated - the response was "no."

Fortunately, the owner didn't seem to be the type that would beat the car - just somewhat ignorant on auto mechanics/maintenance.

Mike


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'90 Legacy LS Wagon, EJ22, NA, 4EAT, FWD w/194K+ miles

[IronMonkeyL255]

I would still change it at 3000 miles.

I have seen many problems with other cars when people wait too long between oil changes.

[Bheinen74]

7,500 is way too long for a oil change. every 3,000 no more.

[HobbyWrench]

Thanks for the comments.

Yes, I was shocked at the seller's response to frequency of oil changes as 'every 7500 miles according to the manual.'

I agree, 3000 miles is a good target, and the seller didn't seem to be the kind that would have abused the car - he was just ignorant on some mechanical aspects.

The car for sale had some other good qualities, so I'm trying to gauge what type of damage this practice may have caused. He claimed to have regularly checked it between changes, and the compression seemed to be up at ~180psi in all 4 cylinders.

Mike

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'90 Legacy LS Wagon, EJ22, NA, 4EAT, FWD, 194K+ miles

[IronMonkeyL255]

It sounds like it didn't do any real damage. I would run a real good cleaner (like seafoam) through the system the next one or two oil changes to get any kind of sludge buildup out of there. If he didn't really beat on it, it should be good.

I do beat on mine, so I make damn sure to change it every 3k, and haven't had any engine issues related to oil (cracked radiators are another story).


Quick story: guy has a WRX and asks the dealer how often should he go between synthetic oil changes. Dealer tech tells him 10k miles. He comes in to us and yell at us because he thinks we told him that. His turbo bearings died, allowed the shaft enough play to shear off the ends of the compressor turbine, sending them into the cylinders.

All that because someone told him to change his oil every 10k........

[tmarcel]

Only real way to know your oil change intervals is to have a sample tested after changes. They can give you good feedback based on the oil you were using and whether or not you can push it out further or not. Generally, the oil is usually good to go on, but the filter needs to be changed more often. Obviously you want the oil to hold up and do its job, but dirt and foreign material will kill bearings.

IronMonkeyL255,

FYI...The compressor wheel is not the turbine. Those bits that sheared away from the comp wheel were the fin tips and maybe housings bits. Also, failing bearings can be anything from the journal bearings to a thrust bearing. What you describe was likely a thrust bearing failure. Those easily can go out from over boosting as they're wimpy stock 270*, soft metal bearings.

HobbyWrench,

The motor sounds like it's okay at least from what you say. Besides man, it's an older vehicle w/ relatively high miles so I wouldn't be that critical. Also, I've seen pressure gauges be wildely off. Anywhere from 5-30psi depending on the gauge and brand.

[subytech]

Just a side note, my bro is in the army and he tells me that they amost NEVER change the oil in Humvees. Every few months they have to send a test sample from every humvee to a lab, it gets tested and based on that they tell them when to chainge the oil. My bro has been in the army for amost 12 years now and he told me hes only had the oil chainged on one of his humvees once in that whole time, he also told me the only thing rarer than an oil change is a blown engine, this goes for both the duramax diesels and the V-8s!

[IronMonkeyL255]

FYI...The compressor wheel is not the turbine. Those bits that sheared away from the comp wheel were the fin tips and maybe housings bits. Also, failing bearings can be anything from the journal bearings to a thrust bearing. What you describe was likely a thrust bearing failure. Those easily can go out from over boosting as they're wimpy stock 270*, soft metal bearings.

I consider that whole assembly as the compressor turbine, since it wouldn't do much compressing without the fins........

The point was that he was told to go excessively long amounts of time between oil changes, and as a result his fully stock WRX was disastered.

[tmarcel]

FYI...The compressor wheel is not the turbine. Those bits that sheared away from the comp wheel were the fin tips and maybe housings bits. Also, failing bearings can be anything from the journal bearings to a thrust bearing. What you describe was likely a thrust bearing failure. Those easily can go out from over boosting as they're wimpy stock 270*, soft metal bearings.

I consider that whole assembly as the compressor turbine, since it wouldn't do much compressing without the fins........

The point was that he was told to go excessively long amounts of time between oil changes, and as a result his fully stock WRX was disastered.

Well "considered" is one thing and what is - is another A turbocharger is comprised of three sections: 1.) Compressor, 2.) CHRA, and 3.) Turbine 'generally speaking'. The turbine of a turbocharger on a gasoline automotive application 'is' the hotside. That's the housing and the wheel to be more specific.

As far as the guy w/ the WRX, I would have to see the failure to understand it better. Journal bearings (the ones on the shaft that literally float on oil and also float on the inside of the CHRA housing can get scared up really bad, thus losing oil psi. However, what you described sounds more like a tyical failed thrust bearing. When they begin to let go, the shaft laterally moves toward the compressor housing and will make contact.

[subytech]

Wow sounds like somebody is really proud of themself, GOLD STAR for jacking the thread!!

[tmarcel]

Wow sounds like somebody is really proud of themself, GOLD STAR for jacking the thread!!

Nope, just being a matter of fact. I was responding to content in THIS THREAD so no hi-jacks.

Three things I do understand (and KNOW very) well are tuning, turbochargers, and motor internals. Sorry if that rubbed you the wrong way, though.

P.S. I admit I know little about transmissions I haven't really gone down that road yet.

[subytech]

Honestly I dont care what you know about turbochargers when were talking about oil, if we were talking about turbochargers then id be glad to hear your opinions, your taking a story that was related to the thread and nitpicking about things in the story that dont matter, we all knew what IronMonkey was talking about without your anal attention to details. Sorry if i seem harsh but you dont need to try and impress anyone around here.

[tmarcel]

Honestly I dont care what you know about turbochargers when were talking about oil, if we were talking about turbochargers then id be glad to hear your opinions, your taking a story that was related to the thread and nitpicking about things in the story that dont matter, we all knew what IronMonkey was talking about without your anal attention to details. Sorry if i seem harsh but you dont need to try and impress anyone around here.

Bro, I could care less. Why would I care about impressing anyone. This is actually how I am in real life LOL! Love it or hate whatever. Like all Internet BS, please don't see my post count on THIS forum for meaning anything. It certainly does not.

My first response in this thread addressed different comments previously made. If YOU do not like me replying back to what folks stated then I don't know what to tell you. I certainly have the right to do so, just as you or anyone else has the right to post. If anything, you're more so picking my posts apart more than I did anyone elses.

To get back on track ONCE AGAIN, I stand behind what I said earlier. Just get an oil sample and be done with it. 7500 miles may be excessive for mineral oil but this engine was not run hard apparently. Double filter changes will be your friend in this case. Debris will kill bearing surfaces.

Personally, I run any of my vehicles to higher change intervals all on synthetic or even semi-syn. Mileage interval depends on the engine manufacturer.

[Legacy777]

Everyone Chill!

tmarcel was pointing out an error in terminology. I've done that many times myself, and I agree, there is a difference between the compressor and turbine.

But anyway...back on the oil topic.

[IronMonkeyL255]

Thank you tmarcel for pointing out how little I know about turbochargers. I understand the principles, but have not been able to disassemble one myself, unfortunately (or maybe fortunately, since I usually disassemble something when it breaks).......

I guess to me the compressor wheel and the turbine wheel look so similar, that I consider them both turbines (but still realize that they function differently and are thusly designed differently).

A quick trip over to Borg-Warner's site is called for to brush up on my turbocharger terminology........


BTW, I still think you came off as an ass, but you were right and I admit it. It says in my sig to correct me if I'm wrong, and you did just that.


Now back to the oil discussion somewhat at hand.

[azn2nr]

my factory turbo visor said to chang the oil every 3000 miles for the first 3 years after which 7500 miles a change is recomended. never had any problems over here. i change my 95 legacy's oil every 10000 miles for the life of the car (owned it for 100k). no isues yet?

[tmarcel]

Thank you tmarcel for pointing out how little I know about turbochargers.

BTW, I still think you came off as an ass, but you were right and I admit it. It says in my sig to correct me if I'm wrong, and you did just that.

Sorry man! Coming off as an "ass" was not my intention I mean that. Hopefully the original poster got something out of the oil change comments though