Synthetic Oil

[WD75MGB]

My 75 MGB has a newly rebuilt engine and I was wondering if I should start off using synthetic oil? I've always had a high-temp running engine and was wondering if synthetic oil would help in keeping the engine run a little cooler, along with other benefits. What are your thoughts?

 

[Bugeye58]

I would start with Castrol 20W50 for the first 500 miles or so. You are going to want to change the oil and filter after running it a bit, so why waste the money on synthetic that is going to be drained anyway. After the initial break in period, switch to the synthetic of your liking. I prefer Red Line, but that is a personal choice.
Some synthetic manufacturers specify conventional oil for the break in period, some don't.
On my race engines, we always break them in on the Dyno on conventional oil, and then switch to synthetic for the power pulls.
I hope I haven't muddied the water too badly.
Jeff

 

[Super 7]

Thats interesting. My engine builder thinks I am wasting my money on synthetic oil, but I run it anyway.

Mine is Jay Ivey, pretty well known for Formula Fords, and Lotus twincams.

 

[Steve_S]

I've heard reports of Synthetic oil not being healthy for B-Series engines. I'll try to dig up the info. I run Castrol GTX 20W-50.

 

[DanZ]

From what I've read, synthetic oil should not be used initially on an new engine because it is so slippery that the rings won't seat properly.

 

[adam90009]

I agree with Dan and I would use synthetic oil in my MGB engine if it didn't leak and burn so much but in the rest of my cars even my V6 in my MGB all use synthetic.