High Mileage Oil for Breaking In

[gamefoo21]

So guys I was wondering, would I be able to use a high mileage oil for breaking in a engine after a total rebuild, or should I just stick to oh say GTX 5w30 and a bottle of the AC Delco Oil Supplement.

I've been pondering this, and wanted to ask the knowledgable folks on here.

 

[Garak]

Originally Posted By: gamefoo21
So guys I was wondering, would I be able to use a high mileage oil for breaking in a engine after a total rebuild, or should I just stick to oh say GTX 5w30 and a bottle of the AC Delco Oil Supplement.

I've been pondering this, and wanted to ask the knowledgable folks on here.


My opinion, and this is only opinion, is to stay away from the high mileage oil for break in, and do what you said - GTX and the supplement. What kind of engine? Non-roller cam?

For my Ford 300 rebuild, I just used GTX and Comp Cams break in additive, which is basically a zinc package. Some would argue that putting high mileage oil in a new engine would prematurely swell gaskets and seals.

A few years back, the guys at Popular Mechanics did a rebuild and used high mileage oil, though. They never reported any adverse effects.

I'd stick to the GTX or something similar for the time being. The savings alone are worth it.

 

[gamefoo21]

Ahh, the reason I ask is because up here a jug of HM oil is the same price as a jug of GTX then you add the cost of the break in oil.

I already have the GTX and the supplement, so for this round I'll stick with it.

 

[Garak]

Originally Posted By: gamefoo21
Ahh, the reason I ask is because up here a jug of HM oil is the same price as a jug of GTX then you add the cost of the break in oil.

I already have the GTX and the supplement, so for this round I'll stick with it.


Yes, the break in lube is quite costly. It adds zinc for the break in of non-roller cams. I don't know if HM oil has more zinc than does normal dino PCMO. You'd have to check the VOAs for that.

For my break in, I went with the lube and GTX. I'll do that for maybe a couple OCIs. In the summer, I'll just run Delvac 15w-40 HDEO (which has more than enough zinc) with no additive necessary. By the time winter comes around, I'll hopefully have enough miles to run a normal PCMO in a suitable winter weight, or run Delvac 1 5w-40.

Maybe I'm being overly picky, but that's my plan. I had excellent results with the high mileage oil before my rebuild, but I'm not planning on using it until I have to, unless I can find some overriding reason to use it earlier.