Burning Oil At 10,000 Miles! (Update 10-03-2015: no more oil burned)

**cyclopathic** · 08-17-2015, 04:40 PM

Call it urban legend, but his has been discussed oh so many times:
http://www.clubcobra.com/forums/fe-t...te-piston.html

this is some tech from a abrasive manufacturer

Crosshatch
Crosshatch is also important because the amount, depth and angle of the crosshatch in the cylinder bores determines how much lubrication the rings receive and the rate of ring rotation.

Excessive shallow crosshatch angles can hinder or slow down the necessary ring rotation that allows the rings to dissipate heat. It can also leave too much oil on the cylinder wall allowing the rings to skate over the surface and the engine to use oil. Too steep of a crosshatch angle may not provide enough oil retention and can result in dry starts and premature ring wear. A steep crosshatch angle can also create excessive ring rotation that accelerates ring and piston groove wear.

Ring manufacturers typically recommend a crosshatch angle of 22° to 32° as measured from horizontal and uniform in both directions.

...if you do some SAE research, you'll find that they can rotate up to around 10 rpms depending on several variables. Sometimes they can rotate at 1 rpm or slower.

For the oil rings, they sometimes are pinned so no rotation on those.

**owl** · 08-17-2015, 05:05 PM

Originally Posted by old mechanic

Pretty sure ring gap offset is 180 degrees, 90 degrees away from the wrist pin ends.

regards
mech

If you go 180 degrees between gaps then rings 1 and 3 will have their gaps lined up. With a 120 degree seperation it doesn't happen. If posssible it's best to keep the upper ring gap away from the power thrust* side of the piston, which is always 90 degrees from the wrist ping. The OTHER 90 degree direction is probably fine. In all honesty I don't know what's worse, inline with the pins or 90 off. Where would the piston rocking make the least difference to the gap?

The proximity of gap to plug is probably the least of the concerns as the piston land above the top ring probably cools down the combustion charge enough.

* The power thrust side being the one forced into the cylinder wall more because the connecting rod is on the other side during the power stroke. Because of the rod angle, the pressure on the top of the piston also forces it sideways a bit. Old steam engines were immune to this because the reciprocating action conversion to rotating movement did not happen directly beneath the cylinder.

**Justamirage** · 08-17-2015, 06:17 PM

Wow thanks for all the expert advice about breaking in my engine, checking my oil on a level surface, and the comparisons to Chevy Sparks and small blocks from the 70s. If I'd wanted a piece of junk to throw away my money on from Government Motors, I would have bought an Aveo (Daewoo).

**cyclopathic** · 08-17-2015, 06:25 PM

Originally Posted by Justamirage

Wow thanks for all the expert advice about breaking in my engine, checking my oil on a level surface, and the comparisons to Chevy Sparks and small blocks from the 70s. If I'd wanted a piece of junk to throw away my money on from Government Motors, I would have bought an Aveo (Daewoo).

Don't take it personally. Other Mirage owners have concern too. Since this is 1st occurrence, and noone else had witness this they're somewhat skeptical. There could be other explanations on why your oil is getting low besides burning.

For example you may have a leak, oil can be not draining to the pan at the time of checking, wrong oil viscosity, etc. Pls bear with us.

**debburyl** · 08-17-2015, 09:07 PM

That's Not Wright!!!!! Mine has 9,200 and doesn't use NO Oil!!! That Mirage needs to go back to the Dealer ASAP!!

**owl** · 08-17-2015, 09:58 PM

Originally Posted by cyclopathic

Call it urban legend, but his has been discussed oh so many times:
http://www.clubcobra.com/forums/fe-t...te-piston.html

Ring rotation is an absolute fantasy, especially when you say a cross hatch does it. Let's pretend a single spiral is cut in the cylinder. There may, possibly, be a tendency for the rings to follow it. Now, cut another spiral exactly the same as the first, but going in the opposite direction. The two grooves now form a cross hatch...AND they completely cancel each other out as far as giving rings any turning force whatsoever.

As far as cross hatching goes there is less and less need for it as cylinder finishes and roundness get better from the factories and piston rkngs keep getting thinner.

A 1/4 inch wide Harley ring along with a back yard bored cylinder may well require a 60 grit cross hatch to get seated. A 2mm thick modern ring sliding in a super fine honed or plated cylinder does not.

Please don't give me that stuff about oil retention, either. Look at a really high mileage cylinder. The rings have worn it mirror smooth and yet they STILL have no problem retaining oil. Then look at all those exotic chrome or nickasil bores. Do you honestly think they'd be so crude as to butcher them with some hand hand drill cross hatch?

**R01k** · 08-17-2015, 11:01 PM

I have 9100 miles and mine doesn't consume oil.

**Justamirage** · 08-18-2015, 08:40 AM

Duh, yeah maybe the viscosity is wrong. I should stop using 20W50 maybe?

Originally Posted by cyclopathic

Don't take it personally. Other Mirage owners have concern too. Since this is 1st occurrence, and noone else had witness this they're somewhat skeptical. There could be other explanations on why your oil is getting low besides burning.

For example you may have a leak, oil can be not draining to the pan at the time of checking, wrong oil viscosity, etc. Pls bear with us.