Remember This When Trying to Find Which Transmission Fluid You Need

John Baker|Jun 26, 2017 8:43 AM

Take a look at just a few of the dozens of automatic transmission fluid (ATF) specifications on the market:

ATF+4
Mercon V
Mercon LV
Dexron VI
ATF DW-1
ATF T-IV
SP-IV
Toyota ATF-WS
Honda DW (ZF
Diamond SP-IV

You’ve likely heard the term analysis paralysis.

That’s what many people feel when they scan the shelves at Advance Auto in search of transmission fluid. They just want a quart or two of ATF to top-off their vehicle, but instead they must decipher a series of hieroglyphics or face the specter of ruining their tranny by choosing the wrong fluid.

There’s a sure-fire way to avoid this hassle.

But first, check out this survey by the Petroleum Quality Institute of America (PQIA), which confirmed what many already know about buying ATF – the specifications listed on ATF labels can be confusing and misleading.

One reason is the sheer number of ATF specifications on the market. Interpreting the made-up words (“Mercon” and “Dexron” sound like diabetes medication or the latest U.S. Defense Department initiative, after all) leaves you shaking your head and vowing to service your transmission next spring.

It wasn’t always like this. At one time, Ford Mercon- and GM Dexron-type ATFs dominated the market and reduced your choices to a manageable few. Today, demand for those fluids has slipped below 50 percent and is declining as original equipment manufacturers (OEMs) continue to introduce their own, proprietary specs.

What is an ATF spec?

Simply put, it’s a set of performance standards. It’s not an actual fluid, meaning you don’t go to NAPA in search of Mercon or Dexron transmission fluid. You go in search of a fluid that meets the Mercon or Dexron specification. In an attempt to make it easy for you, many ATF manufacturers print those specs in giant letters on the label. Judging by the survey, though, it’s not working. This means the fluid was subjected to – and passed – a series of performance tests stipulated by the authors of the Mercon or Dexron specifications.

Today, it’s normal for most OEMs to author their own performance specifications rather than recommend using a fluid that meets a different OEM’s specifications, for example Mercon or Dexron. You can blame it on technological advancements that have made vehicles tougher on transmission fluid than cars of yesteryear. An automaker that introduces its latest 500-hp land rocket wants to be sure you’re using a transmission fluid capable of standing up to the intense heat and stress churning through all those gears.

It may also have something to do with money. Brand XYZ would rather you buy Brand XYZ transmission fluid than another company’s fluid, which helps explain why some OEM-branded fluids are so expensive.

That brings us back to analysis paralysis.

How can we cut through the confusion and make transmission fluid selection easy? And how do we do it while meeting the performance demands of most modern automatic transmissions?

One transmission fluid to rule them all

That’s a bit of hyperbole in honor of my favorite trilogy about hobbits and orcs, but it’s not far off.

We formulated AMSOIL Signature Series Synthetic Automatic Transmission Fluid and OE Synthetic Automatic Transmission Fluid to take the guesswork out of ATF selection. Both fluids are recommended for most of the common ATF specs on the market.

Mercon V? Check.

Dexron III? Check.

ATF+4? We cover that, too.

We take convenience a step further with our online Product Guide, which tells you which fluid your vehicle needs.

LOOK UP TRANSMISSION FLUID FO MY VEHICLE

If you tow, haul or engage in other types of severe service, use Signature Series Synthetic ATF. If you stick to the highway and mostly run to work and home, OE Synthetic ATF is your best bet.

So, when it comes to finding the right transmission fluid, forget about the hieroglyphics and just remember these six letters: AMSOIL.

How to Test Engine Compression

John Baker|Mar 13, 2017 2:16 PM

Testing engine compression in the AMSOIL mechanical lab.

Engine compression = engine power.

A simple equation even we non-engineers can understand. Compression refers to the pressure your engine generates inside the cylinders while it’s running. How much pressure the engine produces and how well it converts that pressure into usable work influence your engine’s efficiency and power.

How it all works and how wear and deposits can erode compression (i.e. horsepower) over time are interesting topics you can read more about here. But today, we’re talking about how to test engine compression.

For this example, I used my 1998 Toyota Corolla. Don’t laugh. I paid cash for it and it runs as smooth as a sewing machine. I also sought the help of Pat Burgraff, one of the techs in our Mechanical Lab. Pat knows his way around an engine.

#1 Ensure the vehicle won’t start when you crank it over

Testing compression requires you to crank the engine several revolutions, and you don’t want it to fire in the process. Remove the fuel-pump and fuel-injection fuses so you’re not dumping gas into the cylinders each time you crank the engine. Then, disconnect the coil packs. Bear in mind the process for your vehicle may be different from the images here.

#2 Pull the spark plugs

Label the plug wires so you return them to the correct positions. Otherwise, your vehicle won’t start when you’re done. Thread the compression gauge into a spark plug opening. Take care not to cross-thread it. You can get a compression tester for less than $50 at most auto parts stores.

#3 Crank the engine

Have a helper crank the engine 5-10 times, or until the needle on the compression gauge stops ratcheting up. Note the psi and move to the next cylinder.

Thread the compression gauge into a spark-plug hole.

Crank the engine until the gauge stops ratcheting up.

What’s considered normal compression?

Here’s where things grow murky. “Good” compression depends on the engine. Unfortunately, engines don’t come with their proper compression stamped on the outside. But a good rule of thumb says that each cylinder in a mechanically sound engine should have compression of 130 psi or higher. While I’ve seen some people claim 100 psi is sufficient, the gearheads and other sources I’ve consulted consider that too low.

In addition, you want consistency from one reading to the next. Again, a good rule of thumb is no more than 10 percent variation between any of the cylinders. That’s not to say 15 or 20 percent variation in one cylinder means your engine is junk. But a good, healthy engine should demonstrate minimal variation.

My trusty Corolla nailed the test, making between 165-175 psi in each cylinder.

If one cylinder has low compression, try pouring about a teaspoon of oil into the spark-plug hole and retesting. If compression increases, it’s likely the rings are stuck or worn. The oil acts as a seal and helps close the gap between the rings and the cylinder wall through which the cylinder is losing pressure.

If that doesn’t work, it’s possible the valves or valve seals are worn.

If you suspect stuck rings, try an engine flush designed to clean deposits, such as AMSOIL Engine and Transmission Flush. You can also try a fuel additive that cleans pistons, like AMSOIL P.i.

Word to the wise: you may illuminate your check engine light performing this test, as I did. It went off by itself after driving a few miles, though.

Tag: maintenance