Ask Honest John

Honest John Classics Ask Honest John » Will an OAT antifreeze cause problems with my 1978 MGB?
Selling your classic car? It's FREE to list your car on Honest John Classics | No thanks

Will an OAT antifreeze cause problems with my 1978 MGB?

My 1978 MG MGB had an engine rebuild six months ago. An OAT antifreeze was put into it. I have read that this may cause a problem to older engines (water pump seals, gaskets, some solders and metal bearings). Is this likely to be a problem for my engine and should I have it changed for a silicate antifreeze?

Asked on 6 March 2017 by John Serenyi

Answered by Keith Moody
As a rule of thumb, cars built before 1998 generally do not need an OAT-based antifreeze. Speaking from personal experience, I would recommend keeping it old school and using an anti-freeze that is non-OAT based and therefore does not contain silicate.

Looking for a garage you can trust? Honest John's Good Garage Guide has thousands of reader recommended garages, plus how-to guides and tips on servicing.

The Good Garage Guide
Similar questions
I hear a gurgling sound in the dashboard of my Volkswagen Passat and I'm losing antifreeze. I don't see any leaks. Do you know what the problem could be?
I am in the process of rebuilding an engine from the late 1940s. The recommendation, which I am following, is to use running-in oil for the first 500 miles to ensure a good bedding of the piston rings...
I use Castrol XL30 monograde oil in my Ford E93A engine and bulk buying is cheaper. What would be the shelf life of the oil?
Related models
Good to look at, fun to drive, amazing parts availability, the archetypal classic roadster and coupe