Puff of smoke at cold start-up

[American Pie]

Our '96 Avy occasionally huffs a big cloud of smoke at cold start-up, especially when it was driven on the highway just before shutting down the evening before. A little more info: it's got 180K, and has been regularly serviced by me and the PO. Just after I bought it a year ago I ran Auto RX through it, flushed it with dino oil then switched over to 10W-30 Mobil 1. It runs great, and burns about a quart every 1500-1800 miles.

Are these engines known to develop valve guide or valve seal problems? I'm wondering if the Auto Rx possibly damaged the valve seals. I didn't notice the smoking BEFORE using the Auto Rx, but it might have been doing it all along; I'm not sure.

I've also thought of another possibility: some of the oil drain-down passages in the heads are partially blocked due to sludge, and oil pools in the heads during highway driving. It might sit there, around the valve guides overnight and seep down into the cylinders where it gets burned away upon the start-up the next morning. I haven't pulled off a valve cover yet to see if this engine is a affected by the common sludge issue, but as I said it runs fine with no apparent oil pressure problems.

I do have another bottle of Auto Rx I can run through the engine if necessary. In any event, I'm thinking about switching back to dino oil and possibly from 10W-30 to 10W-40.

Any ideas? If the oil usage doesn't get any worse I'm not too concerned, but the big cloud of smoke is kind of disconcerting.

[bob2]

ither ditch the mobile 1, or go to a synthetic/dino blend.

your avy was not designed to use synthetic. if it was the rubber inside the engine would be of a different composition. dino oil has additives that keep the neoprene alive. synthetic does not, or has different additives for the different composition of the seals that are used with it.

for now, fill it with a good oil, like casteroil gtx. use the 10-30 unless it's like, hotter than he77 where you live. when the next oil change comes due, dump a SMALL can of brake fluid into the oil. drive it a couple days, then change it. your problem will be gone

[American Pie]

Bob,

I've been thinking about your post and frankly I'm not sold on the idea of running brake fluid through the motor. Do a search on "engine sludge cleaning" or something related to that and you'll see as many opinions as there are #@&holes. Some suggest flushing it with auto tranny fluid, others Rislone, etc. but many say not to run ANYthing but engine oil in the motor. I used Auto Rx last year based on some positive reports I read on this forum, but now I'm not so sure that was a wise thing to do.

Maybe just a few oil changes (using a high-detergent oil like Castrol) spaced about 1000 miles apart would be the safest and most effective flushing method.

Regarding synthetics, is there something special about the rubber bits in these Toyota motors that requires dino oil? I've been successfully running high quality synthetics (Mobil1, Redline, Amsoil) in many cars for over 40 years. On several cars which I purchased used with fairly high mileage (over 100k) I switched over to synthetics and have never had a problem with oil burning or leakage.

[bob2]

i've put brake fluid in... gawd, at least dozens of cars - every car i've owned, actually. i do it annually, to keep the seals (etc.) working well and the crud, from building up. do as you will...

not certain of the degree of "special need" concerning the toyotas, as opposed to any other car. many people have found that synthetics soon leak, driving many brands of cars.

there are the "high mileage" oils... but i'd wager that if you use them you will be putting the chemicals (in brake fluid) in there that you don't seem to want.

i own a 1mz. i put a small can of brake fluid through it, right when i got it running (swapped the engine/trans when i bought it). only results were all kinds of gunk and funk coming out of the motor, with the oil. it does not leak or burn oil, now.

rislone is really good stuff, maybe too good. i'm unaware of rislone as a method of restoring seals/rubber. on one or two occasions i have seen it loosen so much muck that it clogged the oil filter, and blew the motor! that was long ago, in mostly 371/389 pontiac engines, that used quaker state grease...

if i was a dealer or a shop, and if i risked being sued, i would say put only engine oil in the engine... but i'm not. and you have a money-back guarantee, on any advice i give

[pmesfun]

Originally Posted by American Pie

Regarding synthetics, is there something special about the rubber bits in these Toyota motors that requires dino oil? I've been successfully running high quality synthetics (Mobil1, Redline, Amsoil) in many cars for over 40 years. On several cars which I purchased used with fairly high mileage (over 100k) I switched over to synthetics and have never had a problem with oil burning or leakage.

I don't think so, I am running Valovline FS and no leaks or burning oil. But I replaced all the gaskets except for the rear main seal. The front and rear valve cover gasket were the ones actually leaking.

[efontana]

This is likely a faulty PCV valve, simple and cheap fix.

[American Pie]

Makes sense that it could be a PCV valve, but I installed a new one as part of regular maintenance and it didn't help.

[Jack Deth]

FWIW, my 99 with 80K does the same thing every so often. i've never used rislone, but i do add a half quart of marvel about 1K before i change the oil. i've never used synthetic, just 10W30 dino, usually castrol. i thought pcv valve also. i changed it but it did not help.
this is the interesting part... my upstream O2 sensor, front bank failed. at the same time, the puff of smoke stopped. it was gone for 2 weeks before i got around to replacing the sensor. "the smoke must have been caused by the failing O2 sensor" i thought. nope... as soon as i put the new (denso) sensor in, the intermittent puff of smoke came back. maybe just coincidence, the smoke had never been gone for 2 weeks before or since, i don't know.