83rs50

This is going to be a lengthy post, as I want to be very detailed.


I have a 94 DX coupe D15 SOHC 5-speed, and I've had it for about 11 years now. It had 222K miles when I bought it, and now it's sitting on 386K. From day 1 it's always smoked some when flooring it, and around 260K I was having a problem with it fouling out spark plugs every 2-3K miles. I know the original owner of the car, and it's always had Mobil 1 since new. I was still running that at the time, using 10w40 weight. A coworker and Honda guy recommended switching from synthetic back to conventional oil. I did, again using 10w40, and that got rid of the spark plug problem.


Fast forward to today, and I am having a rather significant oil burning issue. The car uses a quart of oil anywhere from 300 to 500 miles, depending on how much I have to flog it to get around traffic. I've been changing it every 2500 miles since I've had it, and I'm now using 15w40 diesel oil. I AM NOT VERY HARD ON THE CAR. Very seldom does the throttle ever get wide open, it's not a fast car, and I don't expect it to be. The car is obviously daily driven, and on my commute to work, I've been going an extra 5 miles out of my way so I can stay on the highway longer and bypass about 20 stoplights each way to and from work. I don't drive over 70mph so I can keep the rpm's under 3200 while cruising. Other than the oil issue, the car runs and drives great, it gets about 35mpg average, and has ice cold a/c. It hasn't lost any of the little power it originally had.


I enjoy this car, and plan on keeping for a very long time. I am a rather broke fella, so an engine swap is not really in the cards quite yet. I'd like to see if I could squeeze 500K out of this engine, but over the last year, I'm not so sure if it can take it, as I'm sure most of the oil is getting past the rings. It now smokes a little while normally accelerating from stops. As you can see from the last 2 pics, the back of the car stays stained with oil residue.


What I'm asking for advice on is, could I start running 20w50 in it? The area in which I live sees a temperature range as low as 10F, up to 95F. I'm just trying to get the smoking down some and see how far I can stretch the engine. It's been great, and hasn't ever been apart aside from routine gaskets, timing belt and water pumps, and a distributor a few years ago. Any advice would be appreciated, just please keep in mind my very low budget.

Mad Dog Tannen

pushing 400k, it's probably just worn, the oil rings or valve seals are worn and not sealing properly. It needs a new/rebuilt long block.

I have had good luck with high mileage formula oil in reducing consumption.

ezone

Needs rings.
And probably everything else.

I'd be filling it with 0w20 at the next oil change..... It might surprise you.

83rs50

I'm thinking it's definitely the rings. It doesn't smoke upon start up, which usually indicates valve seals. At the moment, I just can't swing a rebuild or new engine. I know they're plentiful and cheap on the used market, but I have a 9 month old, and the wife isn't working, so I'm struggling right now. I haven't tried high mileage oil, but the diesel oil was recommended to do the same thing.

83rs50

I do have access to 0w20, as I work at a Mazda/Chrysler/Fiat dealer, so I'll give it a try next time. I think I'll be due for another oil change in the next week, so I'll definitely post the results once I've been running that grade for a week or two.


I've previously ran Motor Honey along with the diesel oil, and noticed a slight improvement in consumption, probably along the lines of getting another 100 or 200 miles out of a quart. But I'd like to see if I could get back to 1000 miles per quart.

ezone

"Thick" oils can be difficult for the rings to scrape, on the downward stroke they tend to 'hydroplane' over the heavy oil film then on the upward stroke they end up pushing it upward.

Low quality oils and heavy oils tend to cook and coke in the ring grooves, leading to the stuck rings.
Higher quality and thinner oils can resist this and can actually help clean out the deposits over time.

If the oil control rings are stuck bad you may not be able to get 1000/qt without a lot of help. .

Look into GM Northstar (and Saturn?? and others) ring treatment attempts where they filled cylinders with top end cleaner or some other carbon treatment and let them soak into the rings for many hours.
.
I know Mazda had a TSB for doing this on .....one of the small V6 engines from the early or mid 90s for a rattle or knock noise

You have access to Mopars Combustion Chamber Cleaner, that's supposed to be some real good stuff there.

My GFs 01 Saturn was needing a quart of oil @ every other tank of gas when I met her..... I started using the high quality oil we use at the dealer (5w20, and 0w20) and after many thousands of miles the consumption had dropped to about 1500 or more per quart.
Before it got passed to her kid, I did a cylinder soaking overnight with the Mopar stuff, then changed oil and off it went. I really have no idea if it helped or not, they don't tell me anything unless it's broken.

Now the Saturn went to the kids and I got the GF a 2007 Fit with 200k on it.
It came to me with a blown head gasket (due to a broken head bolt) and since I didn't know anything about it I went through the engine and found some seriously stuck oil rings. I let the pistons soak for a week in the Mopar Combustion Chamber Cleaner until I could get back to the project. With a little loving, those rings came unstuck without a lot of effort.....but I replaced them anyway.

Mad Dog Tannen

Interesting, I have always heard to use higher viscosity oil for oil consumption. I will try this on my next oil change as I'm sure my rings are a little worn.

83rs50

Your info on thicker oils makes sense, I've never thought about it that way before. I'm sure I can get ahold of some combustion cleaner, and I'll give it a try soon. I'm not sure what brand oil we use here, but I'll start with running the 0w20.


When I do my oil changes, again, they're done every 2500, I drain the oil, change the filter, and fill it up with 5w30. I then allow it to run for a couple minutes, then drain it again, change the filter again, and fill it with my oil of choice. And I must say, the inside of that motor is rather clean for close to 400K miles.


Thank you again for the info, I really do appreciate it.

ezone

Old school thinking is old.

Modern low and ultra low tension rings vs. old school high tension rings is the reason the 'thicker oil' theories on consumption don't always work as people expect these days.

Low tension rings tend to skate right over the thick oil film, whereas the old school high tension rings could forcibly scrape the oil film down the cylinder.....but high tension caused other mechanical issues we really don't ever see these days, like extreme cylinder wear.

If your oil control rings are completely stuck as I suspect, it may (or may not) take a long time before you could tell a difference in consumption using 5w or 0w oil, but I think it's worth a shot.

83rs50

Thanks bud, it's nice when people actually explain why they're recommending things. I was only 50 miles shy of needing an oil change, and I had my car in my shop today doing a RF wheel bearing, so I went ahead and changed it using the 0w20. I expect to likely blow through that oil like no tomorrow, but I'll stick with it for the long run and see what kind of results I can get.


When you say it may or may not take a long time, are you thinking in the range of 10K to 20K miles? I put around 16K to 17K miles a year, and I have no problem keeping with it. I'm glad nobody tried to talk me into running 20w50, as I cringe at the thought of the oil taking a few extra milliseconds to get to the top end on those winter cold starts. The motor sounds like it has a slight upper end clack as it is when it's very cold, and I can't stand that sound. I typically let it idle until it's about to start moving the temp gauge up before I drive, but during the winter I usually allow it to idle for 5 to 10 minutes, and then just drive very easily until it warms up.

ezone

It took my GFs Saturn (01 SL2, 1.9 DOHC) probably 30k or more before I really could tell for sure it was going further between adding quarts, and I've kept doing it this way the entire time I've been taking care of that car.

(I didn't always keep up on it all that good, I forgot to check oil some weekends and it's been run out of oil a couple times, red "TOO LATE" oil light came on while she was driving LOL but it survived)

I've been with her for 10 years now (we don't live together, we'd kill each other)...and the car has gone roughly 100k in that time. It's got about 170k on it now.
I'd totally expect any of those engines to have quite a bit of piston slap cold and some main bearing rattle when hot.

It was normal to hear them rattle until the pistons got hot....but at 400k yours might have a little wear on them LOL

How long until the compression rings wear out and come out of their grooves?

83rs50

Finished a 2500 mile oil change using nothing but 0-20. Used an insane 7 quarts of oil. I may try bumping it up to 5-20. It's just smoking too badly with the 0 in it.

ezone

That sucks....I suppose at 400k it may just be worn out, time for a ring job if you want to keep it going and reduce consumption.

PCV ok?

83rs50

You know, I've never even checked that before. I'll scope it out tonight. But I'm pretty sure it's just time for a rebuild/replace.