TOPIC:

bountyhunter wrote:

swest wrote: I look back on it now and liken myself to an ape or a dog following his nose. I cost myself a premature rebuild after a disaster that was the result of using this junk.

Steve

I actually worry more about that now as oil makers are changing the oils in response to the FED like taking out all the ZDDP. The really scary thing is the new "SN" service grades with viscosity like 0-20W. The thinner oil is being phased in for exactly one reason: increased CAFE (fuel economy) as mandated by the FED.

If somebody who doesn't know better were to put that crap in a ten year old car, they would be screwed. I cringe to think what it would do in an old bike.

The point is that all through the 60's, 70's and up until around the early 90's each new service grade of oil was unconditionally better than the previous. You just bought the newest grade. That's no longer true. New oil isn't even safe to use in some older engines. I wonder how many engines have been screwed up by people who went to Pep Boys and just bough the name brand oil and put it in their car not realizing that new oil can't be used in old cars.

That being the case, STP might be a good thing. Problem is, how much and when?
Steve

swest wrote:

bountyhunter wrote:

swest wrote: I look back on it now and liken myself to an ape or a dog following his nose. I cost myself a premature rebuild after a disaster that was the result of using this junk.

Steve

I actually worry more about that now as oil makers are changing the oils in response to the FED like taking out all the ZDDP. The really scary thing is the new "SN" service grades with viscosity like 0-20W. The thinner oil is being phased in for exactly one reason: increased CAFE (fuel economy) as mandated by the FED.

If somebody who doesn't know better were to put that crap in a ten year old car, they would be screwed. I cringe to think what it would do in an old bike.

The point is that all through the 60's, 70's and up until around the early 90's each new service grade of oil was unconditionally better than the previous. You just bought the newest grade. That's no longer true. New oil isn't even safe to use in some older engines. I wonder how many engines have been screwed up by people who went to Pep Boys and just bough the name brand oil and put it in their car not realizing that new oil can't be used in old cars.

That being the case, STP might be a good thing. Problem is, how much and when?
Steve

I used to always put in about 1/2 can at each oil change on my bike, a full can on my car engines. I will admit I have no scientific proof of it's benefits. The main reason I might use it today is it restores ZDDP levels, however you can also buy ZDDP in other forms (which I do) and add it to the oil without increasing the viscosity.

swest wrote: OK, here's a text book question to all involved. What is the primary purpose of oil in an engine.
First one that answers correctly gets a cookie. DR
Steve

In conventional bearing designs, if the oil is the ideal viscosity (thickness) and being delivered to the bearing at the ideal pressure, the bearing surfaces do not touch each other: they "float" on the film of oil and thus have no wear (ideally). The oil also conducts heat out and away from the bearing so that it is necessary to have sufficient oil volume flowing through to do that.

If the question:

"What is the primary purpose of oil in an engine. "

is just generic, I assume the answer you seek is to control the temperatures in the engine.

bountyhunter wrote:

swest wrote: OK, here's a text book question to all involved. What is the primary purpose of oil in an engine.
First one that answers correctly gets a cookie. DR
Steve

In conventional bearing designs, if the oil is the ideal viscosity (thickness) and being delivered to the bearing at the ideal pressure, the bearing surfaces do not touch each other: they "float" on the film of oil and thus have no wear (ideally). The oil also conducts heat out and away from the bearing so that it is necessary to have sufficient oil volume flowing through to do that.

If the question:

"What is the primary purpose of oil in an engine. "

is just generic, I assume the answer you seek is to control the temperatures in the engine.

Spoiler, you get a cookie.

bountyhunter wrote: The problem is, some of the info being peddled just isn't true:

How Do Rings Seal Against Tremendous Combustion Pressure ??

From the actual gas pressure itself !! It passes over the top of the ring, and gets behind it to force it outward against the cylinder wall. The problem is that new rings are far from perfect and they must be worn in quite a bit in order to completely seal all the way around the bore. If the gas pressure is strong enough during the engine's first miles of operation (open that throttle !!!), then the entire ring will wear into
the cylinder surface, to seal the combustion pressure as well as possible.


The Problem With "Easy Break In" ...
The honed crosshatch pattern in the cylinder bore acts like a file to allow the rings to wear. The rings quickly wear down the "peaks" of this roughness, regardless of how hard the engine is run.

There's a very small window of opportunity to get the rings to seal really well ... the first 20 miles !!

If the rings aren't forced against the walls soon enough, they'll use up the roughness before they fully seat. Once that happens there is no solution but to re hone the cylinders, install new rings and start over again.

Fortunately, most new sportbike owners can't resist the urge to "open it up" once or twice,
which is why more engines don't have this problem !!

Here's some things I do know to be true:

The steel in rings is much harder than the cylinder wall. That's why the rings pretty readily cut the cross hatch pattern down and seal by "forming" the cylinder to the necessary shape.

There's a very small window of opportunity to get the rings to seal really well ... the first 20 miles !!

Baloney. On my last rebuild, I fired it up at about 9PM on a sunday night and all I had the time to do was drive around my housing area for about 20 minutes at low speed. I then retorqued the head the next day and rode it like a new bike (Keep revs below about 4K, don't open throttle more than about 1/2).

How well did my rings end up sealing? Aside from running better than new, and zero oil usage, I did a compression check from stone cold (dry) sat overnight versus fully hot after running and saw a variation of less than 5 PSI.

I am not saying that winding it up a bit will necessarily keep the rings from seating, but I know for a fact it is not necessary to get good seating and the "20 mile" thing is pure BS.



TO ADD: I believe the reason that they advise against wide open throttle during break in: when the rings are working against the cross hatched surface, full pressure can get the edge of the ring to dig into the cylinder wall and score it. After full break in, the square face of the ring is working against the flat cylinder wall so it is less likely to be able to turn enough to dig in an edge. Like I said, might not damage the engine but probably not good to do it a lot during break in. I have been working on engines starting back about 1967 and the break in advice has always been the same: keep the revs down, don't heavy foot the throttle too much, but do run the revs gently up and then let the throttle close and decelerate to get the rings to press against the cylinder walls.

Gas buildup behind piston ring does help seal rings on certain motors,especially those with lots cylinder pressure..

That's one reason for gas porting of pistons.

swest wrote: In the 70's I put in STP because my motor started to smoke. I ran it until the broken cam chain and the overbore etc to fix it. All the 903 piston pins were blue. The rods were OK so I put it back together. Never use STP on a good engine!
Steve

SuperThickPetroleum,I think the name pretty much says it all!

bountyhunter wrote:

swest wrote: That was a time when 100.000 miles was all you could get out of a motor. Tolerances were loose compared to today's standards. The Z1 came out with roller bearing lower end and tight tolerances all around. Those were the days of Ray Lube (paraffin base) oil and STP, seal swell and all the other crap we as dumb consumers bought up. I look back on it now and liken myself to an ape or a dog following his nose. I cost myself a premature rebuild after a disaster that was the result of using this junk.
You want cheap, you get cheap.
Steve

I remember back in the 60's not that unusual to see MOPAR cars with a 225 slant six that had clocked 150,000 on all original parts (even the water pump and oil pump) just had oil changes and tune ups. MOPAR was all we bought back then, their engines were legendary for being bulletproof.

No question the oil wasn't good then, or more accurately the additives weren't. The base oil used in mineral oils hasn't changed much. The new process of hydrocracking (used on fake synthetic oil) makes it better by removing more impurities but the oil is the same. Bikes had a real problem back then because the viscosity increaser additive would shear out in 500 miles or less leaving your 10-40 oil just being 10W oil....

Ah,I remember all those yellow cans of pennsylvania (spell check! ) grade sludge oil/penzoil on the racks outside every gas station.Then there was arnie palmer and his old tractor!

swest wrote: OK, here's a text book question to all involved. What is the primary purpose of oil in an engine.
First one that answers correctly gets a cookie. DR
Steve

Keep parts from rubbing together and relocate little pieces of trash to the pan/filter.

So if a guy was to take a 900 motor and put new rings it what would be the correct way to achieve the best results?
Prep to cylinder, oil at first start up, and running procedure?

Ive began to wonder about this rotella I've been buying at walmart. Im starting to think there is some "slippery" additive in it and may not be good for breaking rings in?

I've always put in store brand thin oil at break in then dumped it after 500 miles, then put in the good stuff with a new oil filter.

Me too. I think I used Valvoline as the break in oil on the last rebuild. I am too cheap to put expensive oil in when I am dumping it after 50 miles.

I did also follow the old practice of using a 50-50 mix of STP and motor oil as assembly lube when I put the thing together. We always did that when we built motors back in the stone age, they didn't have actual assembly lube back then. We would keep a little container of it along with a 1" paint brush and coat everything going together.

PLUMMEN wrote:

swest wrote: OK, here's a text book question to all involved. What is the primary purpose of oil in an engine.
First one that answers correctly gets a cookie. DR
Steve

Keep parts from rubbing together and relocate little pieces of trash to the pan/filter.

The correct answer is cooling. The guy with the cookie gave a shot gun blast answer. All the rest are correct as well.