Castrol with High Zink Content for classics

[Merc Cruzer]

I know this subject has been beat to death. But I was at Walmart yesterday and found this: Castrol GTX Classic with High Zink Content. I have been adding Zink (ZDDP) to my Castrol 20/50 for years.

JUST AN FYI

[Ken/Alabama]

Flatheads have low spring pressure so most any motor oil will be good. I usually buy the store brand. But that’s just me. No issues after 30 years.

[tubman]

Whatever Dollar General has on sale.

[sshep]

Originally Posted by Ken/Alabama

Flatheads have low spring pressure so most any motor oil will be good. I usually buy the store brand. But that’s just me. No issues after 30 years.

Agreed. I do use GM assembly lube during initial break-in on a new engine but than after that conventional oil.

[Ziggster]

Originally Posted by sshep

Agreed. I do use GM assembly lube during initial break-in on a new engine but than that conventional oil.

Hopefully I’ll be firing up my flathead in the next few weeks, and I was wondering what oil to use. As mentioned, this topic has been beat to death. After doing a bit of reading, I’m just going to use some Shell 10W40 I had lying around. On the issue of assembly lube, Ifound this interesting post here on the barn. I just used some Permatex assembly lube on the oil pump I just rebuilt, and having never used any before, I was surprised at how “thick” it was. The engine was also assembled with lube as well by the machinist (I specifically asked him at the time). Seeing how “thick” the Permatex assembly lube is, I can easily seeing it clogging up an oil filter in no time as mentioned in the attached post. Just thought I would mention it.

[40ford]

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[Krylon32]

The Flathead builder I use has started all my motors with Brad Penn with Zinc oil. No cam problems to date.

[sshep]

Originally Posted by Ziggster

Hopefully I’ll be firing up my flathead in the next few weeks, and I was wondering what oil to use. As mentioned, this topic has been beat to death. After doing a bit of reading, I’m just going to use some Shell 10W40 I had lying around. On the issue of assembly lube, Ifound this interesting post here on the barn. I just used some Permatex assembly lube on the oil pump I just rebuilt, and having never used any before, I was surprised at how “thick” it was. The engine was also assembled with lube as well by the machinist (I specifically asked him at the time). Seeing how “thick” the Permatex assembly lube is, I can easily seeing it clogging up an oil filter in no time as mentioned in the attached post. Just thought I would mention it.

Since you are unfamiliar with GM assembly lube, I will explain. It was originally called GM EOS or engine oil supplement. Due to the contents of it Moly, Zinc, etc.. it will damage the catalytic converter on modern cars. So GM renamed it EOS assembly lube so people would not purchase it and run it in a modern car. It is perfectly safe to run as an EOS in non-catalytic vehicles and I do so for an initial break in period.



Just for the record I always added one small bottle of GM EOS/Assembly lube to my plain old conventional oil in an OT NOS BBC drag car. During oil changes, I always pulled the oil filter and then cut it open to inspect the filter for any signs of the engine being un-happy. GM EOS/assembly lube will not clog your oil filter, period. Maybe there are some actual engine assembly lubes that will, but I honestly would not know which ones.

[Ford Freak]

Originally Posted by tubman

Whatever Dollar General has on sale.

For many years now Dollar General or Family Dollar oil has worked fine for me!

[A bones]

As far as the much abused term Classic goes, the period that needs to have extra zinc is, specifically, the late 60's HiPo motors. They had extreme compression ( for a production car ), with severe-lift lobe ramps. Then shortly after their run, leaded gas was phased out. This brought out the need for hardened valve seats, extra care in cam break in, zinc fortified oil. Some zinc is helpful, but too much not so.
Research has told me that the valve spring pressure, in our motors, ( Unless your name is Lawrie or Ronnie Roadsler ) need only be 40 lbs.
Correct me if you wish.

[SoCalCoupe]

Originally Posted by Ken/Alabama

Flatheads have low spring pressure so most any motor oil will be good. I usually buy the store brand. But that’s just me. No issues after 30 years.

Sounds right to me; never heard of anyone wearing out a flathead cam.



Used to work for a guy that had a sign on his office door, "In God we trust, all others bring data." If you really want to geek out, you could send in used oil samples for analysis to see what's really going on. Likely not necessary considering that the flathead was designed around what was available to pour into your crankcase 80-90 years ago. Nevertheless, could be interesting to those of us who really want to know.

[miniceptor86]

What type of assembly lube needs to “melt off the lobes”? Only assembly lube I’ve used was the consistency gear lube. It would easily blend with the motor oil and not clog anything.