Fellow pre-mixers: How much combustion junk gets in your oil?
 

I've been pre-mixing for almost 4 months now, and it's working great, definatly smoother then the oil inject system. I use a good TCW-3 approved 2-cycle and dump 12oz. in and my average fill is 12-13 gallons, so it's pretty close to a 100:1 ratio.

I changed my oil pan 2,000 miles ago, so I've been checking my oil fairly regularly to make sure everything sealed up correctly, and have noticed that it has a faint gas odor to it, which makes me worry about my side/corner seals. I don't seem to really burn any (no oily smoke), and the level is still very close to the top (the only leak I know of is a very tiny one at the crush washer on my oil cooler).

Does pre-mixing cause combustion gases to sneak by the oil seals and into the oil supply after time, or am I dealing with a bigger problem? I did a compression test 2 months ago and it read 110 fron, 100 rear with equal pressure on all sides, and the engine runs quite well, I'm just worried for my poor baby. :D

Welcome to the wonderful world of premixing.

meanin?

Normal. All rotary oil always smells like fuel, even on brand new mazda reman engines.

No joke? I guess I never sniffed my oil. I just happened to wipe some on my face on accident and noticed this time around. Should I not become concerned about my oil seals until I start losing large amounts of oil and create a smoke screen behind me? :D

BTW, doing two oil changes within 10 miles works really well. I forgot to put RTV on the level sender, and was getting a decent puddle going, so I had to drain it, RTV it, and stick it back on. 2,000 miles later, my oil still looks practically new, and I have pretty much no oil leakage. :D

pretty much.. fuel unburnt during the cranking process gets forced past the side seals and a tiny bit usually gets into the oiling system, just enough to cause the oil to smell like fuel but not enough to dilute it. if the engine gets severely flooded and the oil level rises then you should have cause to be concerned.

I'm in a worse condition than you are. Eventually determined this is normal.

Quite a few others running boosted engines and premix are seeing this fuel/oil dilution problem. I honestly think all engines have blowby to some degree, boosted turbos will obviously have more. Then on top of that, no OMP means the crank oil is not being consumed--so it's more obvious that fuel is being added to the oil.

Myself along with several others I know of are just changing the oil every 1-2k miles and living with the problem.

Much tighter clearancing on the side seals could help minimize the problem but many are not willing to tear down a perfectly good working engine just for blowby.

HTH,

Scott

Hmmm, good thing I don' t have any boost then. :D What are the problems associated with blow-by? I'm assuming your oil could catch fire, and higher oil temps, lower pressure, which right now are no problem on mine from what I can tell.

Ah crud, thought of another question. Would you guys consider 100:1 to be too much for a lightly bolt-on modified N/A engine in good shape? I take it to redline once or twice a day, and don't drive it all that hard (it's my DD).

100:1 is good for just about any type of application. the oil you use however determines how well it will protect the mechanical parts.

Excellent. I've been using the Citgo Superguard Marine Plus TCW-3 certified stuff. It's a bit less then $9 for one gallon.

What brands do you guys normally go with?

i just use anything TCW3 certified that i can round up for highway driving, if i plan on doing some hard driving i will use some of my 2 stroke synthetic oil(Redline or Silkolene).

I get some pretty good blowby... I gain a quart or so every 2000 miles, more if I inadvertently run 50:1 on a tank...

I'm pretty sure my side seals aren't as tight as they could be. It's not a big issue, it seems to lubricate fine, and I change the oil often enough anyway (the guys at the local parts store are starting to wonder... I bring in oil a LOT between my 3 cars).

-=Russ=-

Lol, nice. How does that normally work anyways? I always gave it to my father and he took care of it. Now that I have a house of my own, it's starting to pile up in the garage. Do you normally just take it to someplace like Pepboys and drop it off? :D Those fuckers are going to get pissed when I drag this stash in if that's the case, lol.

Pre-mix usually does not have any direct impact on blow-by unless you're doing it correctly.
A "tight" motor should not allow too much fuel into the oil unless the engine is flooding constantly.
Flooding is one of the major causes of blowing fuel into the oil.
If your motor has high mileage, this can also be the cause.


-Ted

I use this Marine Grade Stuff in a Silver gallon jug called Quicksilver i get at Advance, its TCW3 and about 17 Bucks a gallon, I tried the Penzoil stuff and didn't like the way it looked or smelled, so i pay the extra 7 bux a gallon and get the Quicksilver. My jet-ski buddies swear by it...

Even though I'm premixing now... i still change my oil every 1500 miles to avoid any problems with oil/gas fouling. But then again, thanks to the PA DEP, i'm limited to 4,999 miles on my car a year to beat the emissions regs, so it only gets changed three times.

Most auto parts stores (call around to find one) accept small quantities of oil from individuals. You're limited to some reasonable amount (4-5 gal/week is the limit at the place I go) to prevent companies from dumping oil there. If you have a lot of oil stored up, just take it in a bit at a time.

-=Russ=-

I've been premixing with my omp still on and using TCW3 royal purple for last 6 months, and also get that oil gas smell, but got used to it.

so if premixing when is the suggested oil change to be safe?

and what engine oil and two stroke oil do u guys use

engine oil change is the same interval.

I use coastal two stroke that is TCW-3 cert.

Oops, that should be "...INcorrectly." :P


-Ted

Shell Rotella T 15W40 in the engine
Valvoline "Multi-Use" pre-mix in the blue bottle


-Ted

what is the correct method of premixing then?

Check recommended ratios with the manufacturer...
Use a spout to make things easier
Pour pre-mix before filling up with gas
Top off tank with gas


-Ted

Ted is right..... BUT...... to be sure you get the correct oil/ gas ratio...

I cleaned out a 12 ounce gas treatment bottle, fill it with pre-mix... and toss it in the car... then, when it get gas, i pour the premix down the hole and then add 12 gallons of gas. I don't "fill the tank" because you never know exactly how much is in the tank.. Putting the oil in first allows the gas to wash the oil into the tank and mix it at the same time.

I keep two bottle of pre-mix in the car so that I've alway got one incase I'm away from home.