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What grade oil do you use?
https://slantsix.org/forum/viewtopic.php?t=41401		 Page 1 of 2
Author:  Josh P [ Wed Aug 11, 2010 12:13 am ]
Post subject:  What grade oil do you use?
For a while I've been using Mobile 1 10W-30 and for a while I've been thinking about switching to 0W-30. However, I've been doing too much reading over at bobistheoilguy.com and have been considering moving to 0W-20 instead. In chapter 5 the site mentions that the best oil is whatever oil achieves 10 PSI per 1000 RPM.

So the questions... what oil grades do others use (and what kind of pressure does that put on your oil system)? Does anybody go by the 10 PSI to 1000RPM rule? Any thoughts on the claims made by the site about oil viscosity? Also if anybody has any thoughts on oil selection after doing the oil system mod, those comments would be interesting.
Author:  lindross [ Wed Aug 11, 2010 4:16 am ]
Post subject: 
Valvoline 10/30 conventional and change every 3000 miles. Oil pressure at highway speeds is a nice steady 55lbs and drops to 40lbls hot at idle (this is with a new high volume pump). My other slant runs the same at highway speeds, but drops to around 20lbs at hot idle (factory pump).

I can't see a reason to use 0 weight.
Author:  66aCUDA [ Wed Aug 11, 2010 4:58 am ]
Post subject: 
Josh
I use Mobil 1 0-20 in alot of my slants with no problems. Have been for about 3 years for this weight.
Frank
Author:  Charrlie_S [ Wed Aug 11, 2010 5:26 am ]
Post subject: 
I use "plain jane" conventional 10-30 oil in everything I own (including race cars), with no oil related problems. I buy what ever is on sale. On the race cars I do add a few ounces (2-3 oz per change) of EOS.
Author:  wjajr [ Wed Aug 11, 2010 5:31 am ]
Post subject: 
Miscellaneous ramblings form the paisley Chesterfield:

Keep in mind that these engines are 50 year old technology and tolerances are not as tight as in today’s engines. These engines were designed to use thicker oil films. Additionally most of the slants have solid lifters, not the common roller lifter now found in most modern engines, that, I should think would like a thicker film.

Unless you live in Alaska, and drive at -20 degrees and below I would not be using 0W anything in these old engines.

That being said, a freshly rebuild slant may be able to take advantage of these low viscosity oils, if built to closer standards, with non stock parts.

I understand that all properties of today’s oils are much improved over the gallons of 10W – 40W that was run through millions of 1960 era engines in the day. I guess what I’m saying is: today’s low viscosity oil has been improved where less film thickness is safe and desirable in modern engines, but most likely not ideal for our antique’s with well worn original guts.
Author:  Joshie225 [ Wed Aug 11, 2010 6:03 am ]
Post subject: 
I feel a 0W-30 is a good choice as all oils which are the appropriate viscosity hot are too thick cold and our engines live happily on hot SAE30 oil. I would want to see the specifications of the 0W-20 before I would consider its use.
Author:  Aggressive Ted [ Wed Aug 11, 2010 11:02 am ]
Post subject: 
I run 0-30W Mobil 1 in both my rebuilt SL6 engine and a stock 79 SL6 with over 100,000 miles. Both run 50+ lbs at start up and at 2500 rpm (60 mph) cruise. Hot 600 rpm idle shows 28 to 30 lbs. So the 10 psi per thousand does not apply on both of my motors. I am using stock oil pumps and the same oil gauge and the same type 1806 WIX with built in standpipe filter from NAPA.
Author:  lindross [ Wed Aug 11, 2010 7:18 pm ]
Post subject: 
Quote:
Miscellaneous ramblings form the paisley Chesterfield:

Keep in mind that these engines are 50 year old technology and tolerances are not as tight as in today’s engines. These engines were designed to use thicker oil films. Additionally most of the slants have solid lifters, not the common roller lifter now found in most modern engines, that, I should think would like a thicker film.

Unless you live in Alaska, and drive at -20 degrees and below I would not be using 0W anything in these old engines.

That being said, a freshly rebuild slant may be able to take advantage of these low viscosity oils, if built to closer standards, with non stock parts.

I understand that all properties of today’s oils are much improved over the gallons of 10W – 40W that was run through millions of 1960 era engines in the day. I guess what I’m saying is: today’s low viscosity oil has been improved where less film thickness is safe and desirable in modern engines, but most likely not ideal for our antique’s with well worn original guts.
Yup, I've been taught by that same logic.
Author:  lancer61 [ Thu Aug 12, 2010 6:40 am ]
Post subject: 
I always use what the instruction manual says, if it says SAE 30 then go for it, if you use 0W30 5W30 or 10W30 is more a question of taste (and where you live and what you want to pay, 10W30 might not be a good choice in the upper north of course).

The oil channels was designed for a specific viscosity and that is the same today as it was 50 years ago.

That is at least what I do.
Author:  bigslant6fan [ Thu Aug 12, 2010 8:32 pm ]
Post subject:  -
10w-30 winter,and 15w-40 (diesel)in the summer,these engines ran forever on the poor quality oils of the 1960s,and any modern oils are 10x better.
Author:  olafla [ Tue Aug 17, 2010 8:50 pm ]
Post subject: 
This has been a theme for many threads here on the forum. I think 'lancer61' sums it up quite good. The new synthetic oils in general build a thicker oil film than the old mineral based motor oils, and are much more slippery. They also naturally behave more like multigrades, so there are less additives to achieve that effect, than is used in a mineral oil.
Oils made specifically for diesel engines sometimes contain metallic based detergents that may leave a coating on the combustion chamber, valves and plugs.
The first digit in a multigrade oil indicates how it flows when cold, the second digit indicates the flow when hot. For an old engine; a 0W30 for very cold climates flows like a single grade 0 weight oil when cold and like a single grade 30 weight oil when hot, a 5W30 for cool climates and 10W30 for normal/hot climates. Living in a desert region with an old, worn slantsix will probably dictate the use of a heavier oil, and at the other end of the scale, like Aggressive Ted with an overhauled slant. do like the manufacturers are doing: Go with a 0W30 or 5W30 good synthetic oil. Also make a search for ZDDP here in the forum, and check how the oil of your choice is in that respect.
I'm on a very tight budget myself, but buying first class oil really pays off in the long run.

Olaf
Author:  lancer61 [ Wed Aug 18, 2010 1:36 am ]
Post subject: 
Another oil thing now when it is up on the table, most remanufactured (at least older) engines comes with instructions that you should not use synthetic oil in the engine, any one knows the reason for this ?
Author:  emsvitil [ Wed Aug 18, 2010 1:45 am ]
Post subject: 
Quote:
Another oil thing now when it is up on the table, most remanufactured (at least older) engines comes with instructions that you should not use synthetic oil in the engine, any one knows the reason for this ?
Generally synthetic oil should not be used during engine breakin.


I'd bet that's what they mean.
Author:  Sam Powell [ Wed Aug 18, 2010 5:58 am ]
Post subject: 
I use 10-30 Mobil one, mainly to cut down on "coaking" the turbo.

I read somewhere that deisel oil still has the additive that these solid lifters like. Don't know if it is true.

Sam
Author:  olafla [ Wed Aug 18, 2010 12:08 pm ]
Post subject: 
Quote:
I read somewhere that diesel oil still has the additive that these solid lifters like. Don't know if it is true.
We shall not take over Josh P's thread here, but use the forum's search function and search for ZDDP, which is the common name for the additives you refer to, there are pages full of info about the subject. Diesel oils in general have had a higher content of ZDDP, but the problem is what I mentioned above: Some oils still use detergents that are metal based, and will leave a visible residue in the combustion chamber. In different forums the formation of this residue is actually used as a reason NOT to switch to synthetic motor oil, clearly originating when using some diesel or dual service motor oils. The use of different additives (mainly ethanol) in the fuel for environmental reasons, E-85, and the popularity of small diesel engines in european cars, will lead to changes in the composition of motor oils all the time, and the future synthetic oils will probably cover a wider range of uses, unless the oil companies see it as a threat to their market shares.
I use Red Line 10W30 for my worn engine - I'll try Red Line 5W30 this winter, but will switch to 0W30 after an overhaul (or new valve stem seals, if that helps!). It containes the appropriate amount of ZDDP, but that can also be added separately.

Olaf
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