Transmission and engine oil coolers are an important part of any performance vehicle--actually just about any vehicle if you think about it. Whether it's our own body or your street rod's engine, carrying extra weight takes extra energy, and extra energy creates additional heat. The danger in situations like that is overwork and overheating. Excessive heat breaks down lubricants that, in turn, is sure to damage your engine, and we all know that often leads to expensive repairs or, even worse, breakdowns on the road. The same work/heat relationship holds true for your street rod's transmission, as well.The Summit engine oil cooler pictured here is a perfect example of an affordable and easy-to-install kit that takes oil from the pan runs it through a special "sandwich" oil filter adapter, passes it through four 5/8-inch aluminum cooling tubes, then returns it to the adapter. From there, the cooled oil goes into the engine's oil galleries. The coolers come with the sandwich filter adapter (for use with a Fram PH8A or equivalent filter), universal adapter bushings, 1/2-inch high-temperature/high-pressure hose, brass fittings, stainless steel hose clamps, mounting hardware, and instructions.
Engine oil, transmission fluid, and gear lube are the life blood of your hot rod (or any car, truck, or piece of motorized equipment for that matter), and making sure these fluids are kept in optimal condition is really important for their long-term health. Now, I'd venture to guess that many of us pay closer attention to our street rod'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 and beneficial subject that we should perhaps pay a bit more attention to. I think it'd be safe to say the vast majority of our street rods/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 guilty as charged as well. How about engine oil coolers? You know they're not just for race or tow vehicles--those fairgrounds cruisers that putt for hours around an event end up runnin' at pretty high engine temps. You think an oil cooler might be in order in those cases, too? I think so. Now that you have my two cents worth, let's take a look at some fluid and cooler info that may be of help in increasing the life and mechanical health of our street rods. Though the crux of this story will be oil and trans coolers, I found some good background info on oil that I found interesting, 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 10W-30 or 20W-50 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 5W-30. In a warm climate like southern California or Arizona, a 10W-40 or a 20W-50 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 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. Synthetics were developed with petroleum-based lubes' shortcomings in mind and were specifically formulated to withstand harsh aviation engine demands. To this day synthetic lubricants are the standard in the aircraft industry because of their ability to perform in such harsh environments. Since Amsoil introduced the first synthetic oil for automotive use back in '72, synthetic lubricants have become increasingly popular because of their excellent lubricating properties, greater ability to flow at cold temperatures, and their ability to withstand high temperatures for extended periods of time. In fact, more and more new cars are being delivered with synthetic oil in the crankcase, and they also require synthetic oil use throughout their service lives.
Synthetic lubricants are my personal choice and I use `em in my hot rods and everyday drivers. In fact, the 20W-50 AMSOIL pictured here is exactly what I use in the full-size Dodge pickup I tow my travel trailer with (Candy and I run AMSOIL 10W-40 in our hot rods). And we do run coolers (both oil and tranny) in all our vehicles, too.
From what I understand the two primary differences between synthetic and conventional petroleum oils are the base stock (the liquid that makes up the volume of the oil), and the additive package. There are additives (not to be confused with over the counter parts-store stuff) in all oils that enhance the wear-resistance properties, the ability of the oil to neutralize acids and combustion by-products, and provide corrosion protection for the engine's internal surfaces. The amount and quality of these additives vary from one brand to another and is a critical factor in the ability of any oil to adequately protect an engine in varying driving conditions. As a rule of thumb, you'd figure the cheaper the oil, the fewer additives it has and, therefore, the less able it is to protect your engine.
One reason synthetics are deemed superior is they almost always have more and superior additives than standard petroleum-based products, and the synthetic (versus petroleum-based) formulations enable them to last many times longer than conventional oil before they begin to degenerate. The synthetic base stock, however, is at the heart of the ability of a synthetic oil to flow at cold temperatures and withstand greater amounts of heat over significantly longer periods of time. Petroleum base stocks are sensitive to stress and heat. Additionally, various waxes that are contained in all petroleum products, regardless of how well-refined they are, cause oil to thicken or jell at extremely cold temperatures. At the other end of the temperature spectrum, high engine temperatures and heavy loads (as typically found in towing or high-performance applications) cause these lubricants to break down and the conventional base stock of petroleum can actually boil off, causing viscosity breakdown and sludge formation. And check this out: this can happen at temperatures as low as 230 degrees and, by 250 degrees, many petroleum oils will already be suffering significant breakdown. Synthetic oils on the other hand are engineered specifically to provide all the lubricating properties that natural oil possesses, but none of the cold-thickening or hot-thinning properties of petroleum oil. Synthetics are formulated so they can withstand prolonged temperatures of 300 degrees and still protect your engine. In fact, the American Society of Testing Materials (ASTM) standard wear-resistance tests are conducted at 302 degrees, and in those tests synthetic lubes out-perform petroleum lubricants by a factor of four to one and sometimes more. The point being, synthetic oils have a much wider operating temperature range, by design, than petroleum oils. But performance engines can and will benefit from an engine oil cooler so don't think because you run synthetic oil you can take a pass. This said, an engine oil cooler is an accessory that we should seriously consider, especially since it's cheap insurance relative to our overall street rod investments.
This Summit Racing Equipment offering (PN SUM-G4960A) is a good representation of an affordable cooler setup that'll help your transmission's fluid stay between 160 and 200 degrees F, so that it'll live a long and happy life. Coolers like these are available in a variety of dimensions, in both 3/4-inch thick styles and a heavy-duty, 1-inch thick version. Either way, they feature the tried and true aluminum tube and fin design and are sold with high-temperature/high-pressure hoses, mounting hardware, and instructions.
A Few Words On Transmissions
If you think your street rod's engine works hard, think about what your tranny goes through. Your transmission basically controls your engine's rpm's within a usable range and transmits that horsepower from the crank to the drive wheels no matter how hard you stomp on the gas. This process generates massive heat and, in order to keep the heat relatively low, transmissions rely on a substance (transmission fluid) that lubricates and cools the moving parts. Sometimes the transmission fluid just isn't enough to keep everything cool. There are times when the fluid temperature can exceed the recommended range of 170 to 200 degrees, and when this happens the fluid begins to burn. This decreases the amount of fluid running through your transmission, which in turn can seriously damage parts within the transmission, oftentimes leaving you stranded in the least desirable locations possible.
Installing a transmission cooler is an extra precaution against overheating your transmission, and many people decide to use them in tow vehicles but in performance vehicles, as well. Transmission coolers come in many different shapes and sizes, and there are a few things to consider when choosing one.
Perhaps the most important factor to consider is the vehicle itself. How much does it weigh, and are you going to load it up with cargo (clothes, swap meet parts, and beer coolers) relatively often? Matching a tranny cooler to your vehicle's gross weight is critical to allow this add-on cooler to operate properly. (You can get specifics from the pros by contacting any of the engine/trans cooler advertisers you see here in STREET RODDER).
As is the case with engine oil, AMSOIL synthetic ATF exceeds the performance requirements for domestic transmission fluid applications and provides automatic transmissions and power steering units with excellent lubricating protection and better performance over a wider temperature range than conventional automatic transmission fluids. Being a synthetic it resists thermal and oxidative degradation better than conventional transmission fluids, protecting your tranny and its internals from damaging sludge and varnish deposits. More importantly, it helps prevent component overheating and ensures cooler, smoother transmission operation.
In situations where locations are few and far between like in the close confines of a street rod, coolers with integral cooling fans are the answer. This Flex-a-lite model #4190 is a perfect example. It's a tube and fin design that measures 7 1/2x12x3 1/8-inches and is rated for 16,000lbs GVW. Design such as this provide cooling where free air flow isn't available.
Too low a transmission fluid temperature is not a good thing either, and synthetics outperform petroleum fluids in low-temperature fluidity.
This said, there's a good argument for getting a better education with regards to engine oil and transmission fluid coolers. The pages of STREET RODDER are chock-full of engine, transmission and cooler manufacturers and dealers who are experts, and we urge you to take the time to hit their websites or check in with their tech lines to bone up on the subject. Our street rods are a large investment in both cash and effort and anything that can be done to ensure they stay up and runnin' is worth any of the time and effort needed to keep `em that way. Stay cool, and have fun!
Bustin' Myths About Synthetic Lubes
Courtesy of AMSOIL
Many people with questions about synthetics haven't known where to turn to get correct information. Is it super oil or snake oil? Some enthusiasts will swear that synthetics are capable of raising your car from the dead. On the other hand, the next fellow asserts that synthetics will send your beloved car to an early grave. Where's the truth in all this?
Synthetic Motor Oils Damage Seals
Untrue. It would be foolhardy for lubricant manufacturers to build a product that is incompatible with seals. The composition of seals presents problems that both petroleum oils and synthetics must overcome. Made from elastomers, seals are inherently difficult to standardize. Ultimately it is the additive mix in oil that counts. Additives to control seal swell, shrinkage and hardening are required, whether it be a synthetic or petroleum product that is being produced.
Synthetic Lubricants Are Not Compatible With Petroleum
Untrue. The synthesized hydrocarbons, polyalphaolefins, diesters and other materials that form the base stocks of high-quality name brand synthetics are fully compatible with petroleum oils. In the old days, some companies used untested ingredients that were not compatible, causing quality synlubes to suffer a bum rap. Fortunately, those days are long gone. Compatibility is something to keep in mind, however, whether using petroleum oils or synthetics. It is usually best to use the same oil for topping off that you have been running in the engine. That is, it is preferable to not mix your oils, even if it is Valvoline or Quaker State you are using. The reason is this: the functions of additives blended for specific characteristics can be offset when oils with different additive packages are put together. For optimal performance, it is better to use the same oil throughout.
Synthetics Last Forever
Untrue. Although some experts feel that synthetic basestocks themselves can be used forever, it is well known that eventually the additives will falter and cause the oil to require changing. Moisture, fuel dilution and acids (the by-products of combustion) tend to use up additives in an oil, allowing degradation to occur. However, by "topping off", additives can be replenished. Through good filtration and periodic oil analysis, synthetic engine oils protect an engine for lengths of time far beyond the capability of non-synthetics.
