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Q&A with Kit Foster: February 16, 2012


Q. The advice you gave Dave Stanton (Q&A, Jan. 5) is so wrong that if he follows it, he will seize his engine. The flow-through filter he intends to use on his 1951 Buick allows the oil to flow unrestricted. His oil pressure will be zero! The engine was designed for a by-pass filter, which needs to be restricted. The orifice on the return (out) side of the filter should only be between 1/26 and 1/32 of an inch, not the 1/4 or larger that is found on a flow-through filter.

Joseph Tomaeno, Bartlett, Ill.

A. Ah, so there are problems with flow pressures, if the different outlet orifices are not taken into account. I’ve advised Mr. Stanton. I wonder if the filter bracket from a circa 1960 Rambler American would be a good solution. Or was the Rambler engine modified for a smaller orifice? Speaking of the Rambler setup, read on.


Q. Anent your comment in the Jan. 5 issue, “[Rambler] mounted the filter gasket side down, which must have made for messy changes”: Yes it would, if you insist on unscrewing the filter first thing after shutting the engine off. Simple remedy: Don’t do that. Pull the drain plug, lube the chassis, all the usual things that you futz around with while the oil is draining. By the time you get to the upside-down filter, it will have drained pretty much dry. So you see that this design actually spills less hot oil on you than the inverted kind does.

George Hamlin, Clarksville, Md.

A. How soon we forget the days of Lazy-Lube, when there were plenty of chores to be done on all cars while the oil was draining. Actually, I think the messiest filters to change are the ones with a horizontal orientation. We had a Peugeot whose filter was not only horizontal, but nearly inaccessible. Changing it always involved an oil bath – for the mechanic. Some spin-on filters have check valves that prevent the oil from draining back when the engine is off. This means that oil pressure builds up faster, theoretically reducing wear on cold starts.

All of this discussion on check valves and filter orifices highlights the subtle, often hidden differences in filter setups, and in filters themselves. Just because a filter fits, doesn’t mean you should use it. Check to see which one is really specified for your engine.


Q. I am mailing you an article taken from an Antique Auto Club newsletter stating that under no circumstances should “extended life anti-freeze” be used in cars over 10 years old. It’s OAT or Organic Additive Technology and will attack gaskets and gasket cement, causing leaks. The safe type is IAT or Inorganic Additive Technology. Brands to be avoided are Prestone and Zerex G-05 in the gfld container. “Avoid any extended-life.” Acceptable brands are Peak, Peak’s HD Sierra and Zerex Original Green in the white container. Since there are no credits for the article, I question its validity. Furthermore, I have 30 old cars and have been flushing and using extended-life antifreeze. In stock, I have Prestone and O’Reillys and neither container has a warning, nor does it reference OAT technology. HELP!

Julius Alexander, Bloomington, Ill.

A. The newsletter article you sent appears to be a compilation of several items, one of which came from the Auburn Cord Duesenberg Club Newsletter and another was apparently found online. They both repeat criticisms that I’ve heard and read elsewhere. The new OAT “extended life” coolant, called Dex-Cool by General Motors but available with several other names (and perhaps other formulations), is intended for new cars with sealed cooling systems and is said to be good for 150,000 miles. It is easily distinguished from old ethylene glycol (IAT) anti-freeze by its orange color (IAT is green). There have been many reported problems with OAT, even in newer engines. Some attribute these to cooling systems running at low coolant levels. The contention is that air in the system causes corrosion and contamination of the coolant, eventually resulting in “orange mud.” A common cause of air in the system is a faulty pressure cap.

The effect on older engines is not clear. Old engines frequently run unpressurized, and therefore may have air in the cooling system naturally. For this reason, I would not use OAT coolants in an old car. These coolants were developed to extend service intervals in new cars. I don’t see any real advantage to using them in old cars, where one is unlikely to drive 150,000 miles in a lifetime, and where it will probably be necessary to change coolant and flush the system anyway. As to whether you risk damage by continuing to use OAT in your 30 cars, I simply do not know. Readers with experience, either pro or con, are invited to comment.

To submit questions to this column: E-mail or mail to: Q&A, c/o Angelo Van Bogart, 700 E. State St., Iola, WI 54990-0001.

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