clearance vs. oil pressure......

[Adjuster]

I coated the bearings too IJ.
Two reasons.
1) To decrease the clearance as much as possible w/o causing a wear problem.
2) To protect them in the case when there is contact with the crank journals as a last line of defense against wear.

The more metal to metal contact you have, the larger the bearing clearance becomes and the more likely you are to have the oil displaced at lower pressures, so you get acclerated wear at idle with worn out bearings where the oil just leaks out v/s being held in place and doing it's job.

Other idea is using the best oil you can, in a nice thick weight. (Less likely to be sheared off, and better oils have better anti wear additives like zinc that tends to protect the bearings when the journal comes calling.)

I think the best oil for the money here in the States is Shell Rotella T Synthetic from Wall Mart. (You can buy it in 1 gal. containers for about 15.00 each.) This oil is formulated for long haul semi truck diesel motors, holds up to high temps your turbo engine will subject it to, has plenty of zinc and other additives to protect your engine from wear, and being a pure synthetic, will not break down or form sludge as easy as the blended oils out there. (Mobile one is another good choice, but is more money, and has less addtives so it can be "cat" safe on gas cars.)

I found this stuff looking for a good oil for my KTM motorcycle. Excellent stuff, and I've changed over to this from Mobile one in all my cars too. (higher oil pressure at idle is just one benefit, better soot control, corrosion resistance and other positive features override any concerns about clogging up a cat with excess burned off zinc over time.)

Interesting oil reading. http://www.xs11.com/stories/mcnoil94.htm

More interesting info. http://motorcycleinfo.calsci.com/Oils1.html

 

[jetjock]

Sorry Adjuster, I know we've been here before and while it's obvious you're more oil knowledgeable than most people I'll repeat it again: While RTS is a great oil is it *not* a synthetic. It's a Group III. Calling it a "pure" synthetic is just plain wrong. The "thicker is better" thing is mostly wrong too but I won't argue that point since it does have it's place in certain applications.

 

[Adjuster]

There are two types of Rotella T.
One is a 100% group III, the other is "Synthetic". (The Rotella T Synthetic in the blue bottles is 87% group III, and blended with the better stuff for the other 13%. The stuff in the white bottles is a group III oil, and is better than most group III's due to the additive package, but your right, it's just another group III oil.)

Thicker is better for what I need in an oil. As I'm sure your aware, oils act differently when cold than hot. Most mineral oils when cold become too viscous to be pumped well, so you get bearing wear as a result of low oil flow when it's cold.
"Synthetic" oils generally are very easy to pump when cold, and even the 50 weight oils pump well down into the -f temps. This multi weight 5/40 oil is like water when poured out of the container, but instantly raised my oil pressure more than 10 psi over what I was running before. Nice in my book for what they are charging for this oil v/s a "pure" synthetic oil like Red Line that is 9.00 or more a quart, or 36.00 per gallon v/s the 15.00 I pay for the Rotella T Synth.

The fact that it's approved by all the major diesel truck motor builders on the planet is a good thing too.

I have to admit, I just found out this oil is only 87% group III, and 13% PAO/Diesters. I might switch back to the Mobile one 15/50 oil, then again, I might not as this Rotella T/Synth is less money, and appears to be working very well in my cycle and cars.

I suppose with the filter setup on my Supra, and the fact that this commercial grade oil is better than just about any "car" rated oil, I doubt I'll have problems anyway.

 

[jetjock]

No beef. We agree on way more than we disagree on but you're still wrong. I'm talking about the "blue bottle", Rotella Syn 5-40, not the 15-40 in the white jug. RTS 5-40 is a group III. It's not PAO based. Where are you getting that info? Do you honestly believe PAO basestocks could be included for RTS's price? There's a reason it's cheap you know

Almost everything else you stated is true and I in no way want to badmouth RTS. It's an excellent oil with a robust add pack and I've used it for years in my Vulcan and my other cars. I've also used it in the Supra. As I've stated before some Group IIIs come very close to true syns in performance. RTS is without question one of the best oils on the market, especially considering it's price/value, but it's still a group III and although it works great there are "better" oils to be had.

RTS will not hold up to a long OCI like a group IV or V for example. (Before you quote the long OCIs used in the the trucking industy keep in mind big rigs employ depth filtration, as do I).

So yes, for those out there still ignorant enough to be changing their 7-8 buck/quart group IV or V oil (and filters) every 3-4k miles RTS would be the cat's meow. When I think of all the perfectly good Redline, M1, RP ect that gets tossed at 3k miles I can't help but shake my head.

Frankly, these days one could use the cheapest SL or SM rated oil one could buy and as long as it was changed every 3-4k the engine would go 200K miles. Even modern Group IIs bear no resemblance to those of 10 years ago.

 

[Adjuster]

I belive in good filters too Your right on the group III blend, I was misled, so thanks for making me read everything again to be sure. It appears the RTS in the blue bottles is 87% Grp.III and 13%PAO.

The Canton/Mecca depth filter is full flow with no bypass allowed. (or needed since it flows more than paper filters dirty or clean.)

Oil guard bypass filter for what the other depth filter missed. (Claims it's rated to 8 microns for the full flow setup, and the oil guard claims down to 1 micron or better, so I suppose the oil in my Supra should be pretty dang clean, for a long time.) I know the TP bypass filters are cheaper, but the few dollars difference saved using a roll of TP v/s the wound filter element of the oil guard is worth the money in my book. Besides, you only need to change this filter about one time a year at the most. Same goes for the full flow filter, change it every 14k, which is more than a year in my car. (But I generally change my oil 2x per year, but I'm going to extend that to one time a year now with these better filters, and have the oil tested mid year to be sure it's fine.)
Here is my filter setup. Oil guard where the vapor canister used to live. Canton on the apron between the motor and the oil cooler/Tstat.

 

[Adjuster]

One place I think the 9.00 per quart stuff is worth the money is in the transmission, power steering system and rear diff.

Those don't get changed as much as they should, and spending a few bucks more for oils you don't change regularly is good insurance for your performance vehicle. (or any other for that matter IMHO.)

 

[figgie]

I thought about putting them in there, but I thought it'd be too cluttered!

Figgie:
If the oil were not allowed to leave the bearing surfaces, you would have mondo pressure with no flow and aside from lack of cylinderwall lube, this would be ideal.
Pressure is a restriction to flow. In a turbo, it is also the byproduct of adiabatic compression, which is NOT a restriction to flow.
By shimming the oil pump, you are NOT restricting the flow to the motor.
The idea to increase the pressure in our motors is to restrict the flow of oil away from mating surfaces. That is, tighten tolerances. The pump is posative displacement, so when the shaft turns, oil moves. The pressure of the system is completely independant of the flow rate due to this fact.

Electric fuel pumps are not PD pumps, they are vane pumps which opperate at a constant speed and flow a rate that is inverseley proportional to pressure. Our oil pumps DO NOT behave in this fashion.
By your logic, you are suggesting that when one shims the oil pump relief, or increases the pressure by means of tighter clearances, the pump of the shaft spins slower. Well, last time I checked, it was connected to the crank by a timing belt.

perhaps i spoke to soon

instead of elecric pumps see belt driven pumps. They are PD but as rate increases PSI increases. At one point something will give (be it the hose, the injectors etc). you are incrasing rate which automagically increases pressure as there is NO WAY to increase area unless we machine the block.

 

[jetjock]

Adjuster: I've seen your filter setups before. They're very well done, as is everything you appear to do. The Rotella thing was my only gripe. Everything else you said is dead on and I can't disagree with your choice of methods or equipment. I prefer TP but that's a personal choice. The bottom line is we're much closer on all this than we are apart and it's a pity more people aren't as informed as you.

 

[Nick M]

I ask this out of curiosity, but if the main & rod bearing clearances are a little looser than what the TSRM calls for, but the oil pump is shimmed, would there still be an increased risk of trouble?

So the basic question is if the bearings are out of spec, will a flow increase delay engine damage?

Yes. But that is all it is, a delay.