I guess the timing couldnt be better though, the freight company dropped off my new block today.

After I pulled back down the driveway, I heard my exhaust rattling, so i revved it a couple times (not high at all, just enough to hear the rattle). Turned the motor off, walked around to the back to inspect the muffler.....black streaks in the gravel.....not good. I check the streaks, seems like a mixture of oil and soot, but seemed like mostly soot from the exhaust.

The motor needed some oil to get it into the "operating range" area on the dipstick, but really not taht much. This means that it's using a quart of oil every 4 or so months, which isnt too bad I suppose. My only guess is that it's the rings going bad, since oil pressure is fine (around 40psi at idle and 60 when on the pedal), and the completely stock, non-rebuilt 305 has over 185,000 miles on the clock.

Should I really be worried about this, or do you think I'll be fine until my new engine is complete? Thanks in advance.

 

I wouldn't lose sleep over it. It could run that way for another 50,000 miles or more as long as you maintain the oil level. The type of oil could also be affecting the consumption.

 

The engine only saw dino-oil up until the past 4 or 5 oil changes, where I switched to full synthetic (mainly because I had a lot of coupons lol), so I'm wondering if the synthetics would be causing some of the problems. But yeah, as long as I check it often it should be fine.

 

A quart every 4 months is pretty good for a motor pushing 200K. I also wouldn't worry about it.

Synthetics are often blamed for "causing leaks" and other oil consumption. I've done some reading about them and it seems that was kind of misleading. They have additive packages that seem to do a better job of cleaning out the old oil sludge, while they leave very little behind themselves from oxidation (remember the old Mobil 1 commercial with the oil in the frying pans?). The net result is they clean stuff out of the motor. Unfortunately, in some cases that "sludge" is actually helping to seal up the motor if you've got a real high mileage engine!

Now, I'm no expert on oils by any stretch and I'm sure I'm not expalining that quite right (and I'm sure there's a lot more to the story than I just gave you), but it's apparently not uncommon for high mileage engines to consume and/or leak more oil than usual when switched over to synthetic. When you get down to a quart every 2 weeks you've got a real problem. Until then, enjoy the car.

And don't worry about black stuff out the tailpipe. Your exhaust system is FILLED with carbon, rust and other crap that gets easily carried out the tailpipes with water vapor and such. Just a by-product of burning hydrocarbons (gasoline) for tens of thousands of miles and shouldn't in any way be confused or associated necessarily with oil consumption. If you're burning any serious amount of oil you won't have to look at the stuff dripping out the tailpipes- you'll clearly see blue smoke coming out the exhaust.

 

Just keep it full and drive it until your done with the new engine. I'd go back to dino juice and run the least expensive oil you can find. No point in wasting cash on the good stuff now.

If you want a real good (bad) example of oil consumption my old 912 stated in the owners manual that 1.5 to 2 quarts of oil consumption in 600 miles is normal. Yes 600 miles not 6000.

 

I'd run it on a good mineral 20w 50. We use it alot here in Australia in Ford and Chev V8's from that era. The 20w 50's are higher in Zinc which is great to reduce ware. Provided your not living somewhere it gets really really cold, we use 20w 50's down to about 3 deg cel.