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MG MGB Technical - Castrol SAE 30

Hi All,

I have just bought some Castrol SAE 30 for the overdrive gear box.Bought at Canadian Tire. It was in the specialty oils section.

The stuff is transparent! It states on the bottle SAE 30 lubricant. Suitable for compressors and other applications where "foaming" would be an issue.

Is this the correct formulation for a MG overdrive gearbox?

Cheers, Neil.P
Neil Peniston

In my OD box I've been quite happy with Redline MTL:
http://www.redlineoil.com/product.aspx?pid=45&pcid=7

Rob Edwards

Neil. Should be no problem. I used to use straight 30 weight oil back in the days when multi-grade oils were not common. For the last 30 years, I have used the same 20W-50 that I use in the engine with no problems noted.

Les
Les Bengtson

Neil,
Most of the cars over here use 20-50. The V8s use a thicker grade but 30 should be fine. If yours is a keepers car, there are some fully synthetic 30 grade oils which would provide more protection. I use a 30 grade in my LT77 5 speed box in preference to the recommended auto oil.
Roger
R Walker

Neil,


Yhat site could answer your question:

http://www.quantumechanics.com/categories.php?op=newindex&catid=11


Cheers,

Jean
Jean Guy Catford

The Castrol 30W non-detergent oil will make a big improvement in the way your OD functions. It will respond to input commands much quicker than with conventional oils. I've been using it for several years now with no complaints. RAY
rjm RAY

Thanks for the input from all of you.

I would still like to know why this stuff looks like water with and obviously higher viscosity. Does not look likel oil! States that is is derived from paraffin { derived from oil} distillates.

All the other SAE 30 products state "motor oil" on the container where as the castrol states merely a "lubricant".
Possibly I am just paranoid, however I do not want to screw up a perectly good overdrive.


Cheers, Neil P.
Neil Peniston

It doesn't have the additives that would make it a detergent oil. Being a single weight oil, it also lacks the various chemicals that allow a multi-weight oil to change viscosity according to temperature. It may look like a very mild lubricant, but it works very well in an OD transmission where no combustion is taking place and no detergents are needed. RAY
rjm RAY

I used to work in the oil additives business. Additives make oil darker. Base oil(unadditized) oil is light in color.

Our customers (Castrol included) had a maximum color specification on additives and were always hoping for lower color additives so their oils would look lighter out of the bottle.

Some of the additives (such as detergents) create foam especially in engine oils. Foam inhibitors are added to control this but it still can happen with additized oil. Compressors use splash lubrication so they really are a challenge on foam as the rods are beating into the oil reservoir all the time. Gearboxes and pressure lubricated engines have less foam problem.

You don't generally don't need detergents or acid neutralizers in gear oils nor do you need dispersants. But, wear inhibitors help sliding surface wear. Friction modifiers should be present for good synchro action.

Generally gearboxes are hard on multigrade auto oils as they shear down the polymers used in them. Some engine oils are better for gearboxes than others as they pay a premium for more shear stable additives.

Synthetics get the multigrade performance with little or no polymers. They are quite shear stable.

Based on the above, I'd be tempted to go with the Redline option. I've used it in my 3 synchro N/O box and have been very happy.

Robert McCoy

I stay away from synthetis oils in OD boxes as we've had considerable trouble with them causing slippage and even destruction of the friction facings. Redline claims their oil is OK with an OD. It may or may not be - it might work on the street but not be up to hard use; either way there is really no downside to just using straight 30 regular oil.
Bill Spohn

Bill, your concern is valid. Synthetics can be used for OD applications but they need the proper friction modifiers so the clutches engage properly. Otherwise they can be too "slippery" and the clutches burn up. Many ATF's are now synthetic. The key is the correct friction modifiers for the clutch design.

Whether or not Red Line does this may be hard to determinve. For ATF they have to meet OEM specs and testing. For our vintage cars there is no such organization.

I don't know how good compressor oil is with clutches and helical or planetary gears, that's why I would be hesitant to go with that in a gear box OD or non-OD.
Robert McCoy

This thread was discussed between 17/08/2012 and 06/09/2012

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