Welcome to our resource for MG Car Information.



MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - Camshaft Break In? VR1 oil update

Ok, I have purchased some VR1 oil. The bottle says it exceeds API services sm/sl/cd, and has ashless anti wear additives and zddp. This oil is also street legal and readily available.

My home test comparing the thickness to my standard 20/50 oil, it is much stickier. When pouring a small amount in a cap, then pouring it out of the cap the VR1 comes out much slower and leaves much more residue in the cap. On your fingers it is also much stickier.

I have a reground "sport" camshaft to break in. I was told to use diesel oil on the break in. I purchased Shell Rotella T 15/40. Is this the best oil to break in a camshaft with or would a straight 30 be better for break in?

Thanks for the input ahead of time.

Check the specs on the Rotella as they have changed also. My local NAPA does not have any old rotella left. I use a product called EOS from my GM dealer. It has not failed me yet. (EOS is Engine oil supplement)
Sandy Sanders
Sandy Sanders

Castrol has answered the call.


LaVerne. Thank you. It is good to know.

Initial engine break in, the first twenty minutes of operation, needs a high ZDDP oil to ensure that the cam and lifters are not damaged. After that, the oil is drained, the filter replaced and fresh oil and filter installed. Now, things become interesting.

My daughter's 77B had a three year old oil line, going from the rear of the block to the oil cooler, break as she was driving at highway speeds. She was not able to save the engine, a rebuild with 2,000 miles on it. Crankshaft had to be turned, but the other parts were in good condition and could be reused. One of the things I noted is that, running the Castrol 20W-50 oil, the rings were not yet seated and the honing of the cylinder bores was still very visible. (Full seat ing of the rings is noted by the entire outer edge being bright instead of showing the blackening from the heat treatment process.)

I would suspect that synthetic oil should be avoided in a rebuilt engine until there are about 10,000 miles on it. The modern oils, as compared to the older blends used back when these cars were built, results in far less engine wear than the older oils allowed. Hence, a longer break in period is needed.

Tom Sotomayor, both a member of this BBS and an engineer, recommended the old standby STP to me during his last visit. It contains ZDDP and, when added to the Castrol 20W-50 oil seems to provide a high level of protection to the cam and lifters.

The Castrol synthetic oil may well be the way to go in the future. But, I can see that using it too early might well cause excessive oil loss on an engine that is not fully broken in and might well delay the break in of an engine.

Food for thought and I would be interested in what others have to say about this.

Les Bengtson

There are two formulas for STP. Red appears to have ZDDP. Blue does not.

Another issue I have heard with synthetics is that the cars leak more. Anyone pro or con on that?

Bruce the info I have has them the other way. Blue with zddp, red without. I will go into it further.


Please don't use oils with anti wear additives while breaking in a new engine!

Use Castrol 30 weight running in oil which has the right amount of zinc or use a CHEAP 10W/40 mineral oil intended for diesel engines which has high zinc but not the expensive anti wear packages.

Use Graphogen or moly disulphide on the cam / lifters but keep it off pistons/rings
Chris at Octarine Services

Nice of Castrol to put out an oil for classics, but why not a conventional oil with ZDDP. Synthetic is good for a new engine but not so good for a 50,000+ engine...I'll stick with VR1 for now
R Dougherty

I ended up returning the Rotella and going to a local machine and purchasing some of their break in oil. They use Joe Gibbs break in oil, it states on the bottle it has high zinc and provides protection for flat tappet engines. I would suggest doing the same to anyone breaking in an engine. Contact your local engine builders and see what they use. I was told most diesel oils now also have low zinc levels.

This thread was discussed between 15/02/2008 and 19/02/2008

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.