Engine oil, transmission fluid and gear lube are the lifeblood of your classic pickup (or any piece of motorized equipment for that matter), and making sure these fluids are kept in optimal condition is really important for their (our vehicle’s) long-term health. Now, I’d venture a guess that many of us pay closer attention to our classic truck’s maintenance than we do our everyday drivers, but I’m sure there’s room for improvement in nearly all cases (I know my maintenance regimen could use some help).

Above and beyond regular fluid and filter changes, oil and fluid temperature control is an extremely important subject that we should perhaps pay a bit more attention to. I think it’d be safe to say that the vast majority of our classic trucks and hot rods are equipped with trans coolers (at least those equipped with automatics anyway), but are they really doing the job? In other words, did we just get to that point in a build and grab any old cooler assembly and stick it wherever we could fit it – and then forgot about it? I thought so, and to be honest, I’m also guilty as charged.

How about engine oil coolers? You know they’re not just for race or tow vehicles. Those fairgrounds cruisers that putt for hours at an event end up runnin’ at pretty high engine temps, don’t they? Ya think an oil cooler might be in order in those cases, too? I think so. Now that you have my two cents let’s take a look at some fluid and cooler info that may help increase the life and mechanical health of our pickups. Though the crux of this is oil and trans coolers I found some good background info on oil that I found interesting and thought you might find interesting, as well. So, let’s start out by taking a look at the fluids we’re trying to keep cool.

Oil Classifications

If you’ve ever paid attention to the small print on a quart of oil I’m sure you’ve noticed some classifications listed there – SAE and API. The SAE (Society of Automotive Engineers) and the API (American Petroleum Institute) classifications actually designate the type of engines for which the oil was designed. More often than not, SAE viscosity grades incorporate “W” numbers when classifying multi-grade oils like 10W30 or 20W50, for example.

From what I gather, the lower the first number, the better the oil will perform in extremely cold conditions. Conversely, the higher the second number, the better the oil will protect at higher temps. If you live in a cold weather state like Minnesota or North Dakota, during the winter months you’d want a lowest number like a 5W30. In a warm climate like southern California or Arizona, a 10W40 or a 20W50 would be a better choice. The API typically uses an “S” designation for gasoline engines and a “C” designation for diesel engines. The majority of today’s oils carry an SH, CF or SJ – CF designation signifying that they are suitable for use in all gasoline or diesel applications.

Petroleum and Synthetic Lubricants

During the course of my investigation into lubricants, I found out that synthetic oils were originally developed more than 50 years ago primarily for aircraft engines. I originally thought that it was a much newer technology. Extremely cold (-120 degrees at altitude) temperatures, high rpm’s (upwards of 60,000), and extremely hot (500 degrees plus) exhaust temps were just way too much for conventional oils, breaking them down in short order.