93 replies to this topic

[hanra]

Thanks for the insight Oldjohnno.

Edited by hanra, 31 July 2014 - 10:52 PM.

[REDA9X]

Obviously the 2 warnings and the reply i wrote wasn't enough. Next time it's a holiday.

Yeah Laz, & you've really shown what you write.. ..you aint real high on the validity factor quotient , eh Laz..

 

Credulity, yes... credibility.. nah sorry, not so much..

 

Whatever big red, warn away.. its just more typical girls school shit anyhow..

[N/A-PWR]

I put 40/70 in my old work horse Motors

New vs Old

[orangeLJ]

Can someone look under the bench for the big hammer? I know its been a while and its probably dusty and a bit rusted, but its still useful.

Edited by orangeLJ, 01 August 2014 - 08:27 AM.

[TerrA LX]

Simple question on oil viscosity

What is best for a holden red 6
10-40
15-40
20-40

Not concerned with brands, that all about you wallet size

You mean 20-50?
I never seen or heard of 20-40.

[REDA9X]

I believe most oils have going away from 20-40 oils, it's usually 15-40 or 20-50. I know I have seen 20-40 though,  think I have an old can in the shed.

[rodomo]

Other tricks were used to limit the lifter internal hydraulic movement range..

Yep, like let them pump up and give them a "feel" clearance even.

[N/A-PWR]

http://www.penriteoi...id_viscosity=22

 

I just use this anyway, Motor Runs Fine.

3.3 Blue Motor in a WB Tonner x 3.55 LSD

[Ice]

So OJ what oil do you recommend for a fresh worked engine after the running in oil has done 500 miles
would like to know what you would use
oh its a 202 of course
thanks

[yel327]

Johnno, what is your take on cars that specify 10W-30 or 5W-30? My V2 CV8, SR5 Hilux V6 and Lexus RX350 all do this. I use Nulon synthetic 10W-40, primarily as most manufacturer's specify if you are going to do any towing, long distance driving or the ambient temp exceed 30deg C you should use 10W-40 or 15W-40.

[hanra]

Johnno what's your opinion of the oiling design of the BMC A-Series mini power unit, as in using the same oil for Diff/gearbox/engine...

[RallyRed]

Probably should mention a few things that not everyone is aware of. Someone has already helpfully shown us the chart showing the relationship between SAE numbers and actual viscosity, and it's plain to see that the SAE numbers refer to a very broad range. So broad in fact that they are almost useless. But it gets worse - if you check the actual viscosities of a lot of common oils you find that they don't match up at all with the SAE numbers and sometimes they are way, way off.
 
I think the reason for this is that while the oil might be marketed as a 20/50 or a 15/40 there's nothing there to say that they are actually an SAE20/50 or an SAE15/40 oil. The numbers are just a sort of a marketing device and aren't SAE numbers at all. As I've said here before, the only safe way is to ignore these numbers (SAE or otherwise) and look up the actual viscosity before you buy. Some of the Penrite stuff in particular is insanely thick. If you don't feel like looking up the viscosities they are listed for some common oils in this page I linked to earlier - http://www.oldjohnno.../OilTables.html
 
The other thing I want to mention is oil pressure, and in particular why we don't want it to be too high. A lot of old blokes are still under the impression that oil pressure matters, and that lots of pressure is a good thing. The reality is that it doesn't tell us much at all. How much do we want? Ideally, at full load we'd want it to be just under the relief valve setting. We don't need a lot of pressure at full load and speed to build the hydrodynamic wedge, the high journal speed can do that by itself. But we do need a lot of flow to keep the bearings cool. I've never seen a crank burnt because the oil was too thin but I have seen them lunched because it was too thick. I'm gonna shout this bit because it's so important : ANYTIME THE OIL PRESSURE IS ABOVE THE RELIEF VALVE SETTING THE VOLUME OF OIL PUMPED TO THE BEARINGS IS LIMITED. YOU DO NOT WANT THIS.
 
Dave, I remember reading in earlier posts that your engines mainly die from big end failure. I'd certainly be trying a (lot) thinner oil in my next build and I'd be very surprised if it doesn't improve the bearing life dramatically. Don't worry about oil pressure; if it has 5 -10 at idle and 20 or so pottering around town it'll be getting the full volume and will live forever. Ideally it wouldn't reach the relief setting until at least 4 or 5000rpms. You'll be assured of a plentiful supply to the bearings and a long bottom end life.
 
Another reason to avoid thick oils is that they don't release entrained air anywhere nearly as quickly as thin ones, and the bubbles are generally bigger. The gauge may show 60psi but if a bearing is fed nothing but air for a second or two at full load then it's all over. Look at what the OEMS have been doing for the last couple of decades - clearances have stayed much the same but oil viscosities have steadily fallen, outputs have increased but engine life has
generally grown longer. Thinner oils just plain work, it's just a matter of losing the preoccupation with the pressure gauge.

..great info O.J. thanks. I always try and learn stuff like this, from guys who know.

In my simple little world I think I understand that you are saying that the oil pressure read by the gauge, which is really just pump output pressure, is of not so much importance. Due to the fact that most engines never die from
"low oil pressure at the pump"" bearing failures .i.e. the bearings don't give a toss about what pressure is on the
gauge/at the pump, just that there is sufficient flow where they are.
Thanks again