Has anyone used Havoline 10w40 in their y blocks?  The zinc numbers look good and the price is right.

I'll let Ted speak on this, but I think that is what the oil he usually uses in his builds has - Valvoline conventional 10-30 or 10-40.


54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ

Evidence indicates the ‘zinc content’ issue is overblown.  It’s not what elements an oil contains, so much as how well it prevents wear.  Because chemical analysis data seems more publicly available than reliable comparative testing, we tend to grasp at straws.

6 VOLTS/POS. GRD. NW INDIANA

I am far from an expert on the subject so take what I say as opinion based on many years of experience.  Other comments or rebuttals always welcome.

As Paul mentions, I use multi-weight Valvoline conventional oil in many of my flat tappet engine builds.  Whether it’s 10W-30 or 10W-40 depends upon the assembled bearing clearances within the engine.  I reserve the use of racing oil for the racing applications or where the oil is being changed on a more frequent basis than I would be doing with a conventional oil.  I do shy away from using synthetic oils on those engines using the older flat tappet camshafts only due to the reduced shear properties of many of those oils which inhibits tappet/lifter rotation.  Those same shear properties are also reduced on oils with less than 30 in their weight classification (ie. 5W-10, 10W-20) and also prevents adequate lifter rotation thus contributing to premature camshaft failures.

The actual brand of oil being used is more about the quality of the oil being used with the zinc/phosphorus (ZDDP) amounts only being a secondary consideration.  The oil does need to be for a gasoline engine as diesel engine oils have a different additive package to compensate for the amount of diesel that goes into the crankcase.  I have observed a noticeable increase in bearing wear over the long haul using a diesel rated oil versus oil designed specifically for gasoline engines.  While a total zinc/phosphorus content of 1250-1350 ppm was the old standard, using amounts that are only half of this has not proved to be detrimental.  When the zinc/phosphorus amounts are reduced, I will typically recommend more frequent oil changes to compensate for the reduced ZDDP amounts within the oil simply being exhausted more quickly.

Always keep in mind that immediate camshaft failures are related to issues other than the ZDDP amount in the oil.  Here’s the link to a list of items that will contribute to camshaft and/or tappet failures.
Camshaft and Lifter Failure Causes – Eaton Balancing 

On the other side of the coin is where there is too much zinc in the oil and that contributes to condition known as ‘zinc overloading’.   An indication of that is pitting on the opening flanks on the camshaft lobes.  Like most long-term camshaft wear conditions, indications of zinc overloading will happen over a long period of time and is not something you will see on a short period of time on a new camshaft.  Zinc overloading can potentially also be present by changing the oil too frequently with a high zinc content oil.  Another scenario is adding a zinc supplement to an oil that’s already high in zinc.  Here’s a picture showing what zinc overloading looks like.
  

Lorena, Texas (South of Waco)