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Most people are familiar with the basic types and brands of two-stroke oil consumed by these engines; however one area overlooked is the oil used in the gearcase. The gearcase of an outboard or stern drive is analogous to the transmission in an automobile, meaning that it channels engine power through a reduction gear system to deliver usable power.
Aerospace Lubricants is well known among hardcore automotive and boat racers for their line of Alisyn fully synthetic oils. What makes Alisyn stand out among other leading synthetic oils on the market is the unique and highly guarded additive package that allows Alisyn gear oil to provide more protection from a lighter viscosity formula, namely, ProGear 21 Type 1.
Alisyn’s custom gear formulas and exclusive additive package were developed through years of extensive race testing and refinement in such applications as SCCA Endurance Cars, Pro Stock, and Pro Modified drag cars, and more importantly, high performance marine gearcases. Additionally, ProGear 21 Type 1 is designed to handle necessary loads while reducing internal gearcase temperatures.
In addition to its primary function of lubricating gears and displacing loading pressures and heat, the Alisyn ProGear 21 oil contains various demulsibility agents, which help retain the oil’s effectiveness, even when water is introduced into the lower unit. This was of particular concern to us, since we felt the lighter oil weight could possibly allow water intrusion in the presence of worn or weakened seals.
For testing, we were provided with Alisyn ProGear 21 Type 1 lightweight high performance gear lubricant and ProPower 21 full synthetic two-stoke engine oil. Of particular interest in this evaluation is Alisyn’s super low viscosity, less than zero-weight ProGear 21 Type 1 lower unit gear oil. That’s right – less than zero weight – when all other gear oils carry a viscosity rating between 80-90W. Alisyn claims increased engine RPM due to a reduction in parasitic drag losses from using this low viscosity gear oil, in addition to providing the best protection available during extreme running conditions. Sound too good to be true? We’ll find out by putting Alisyn ProGear 21 Type 1 to the test in demanding, high performance conditions. Read on…
For testing platforms, we used our finely tuned STV/Mercury 2.5 EFI and requisitioned Herb Terry's very fast Intimidator 21 powered by a Mercury 300X. By testing with 2.5 and 3-litre versions of Mercury’s popular high performance SportMaster gearcases, we could get a fair picture of any RPM or horsepower gains relative to boat weight and setup, as well as oil integrity under intense, yet different operating conditions. Running the gearcase in a surfacing application (such as this test) places maximum loads on the bearing carrier components, especially at 120+ MPH speeds over extended distances.
Before any testing, we went to Ocean Marine in Freeport, NY, where head mechanic Jim Molnar disassembled and inspected the internal components of our Mercury 2.5-litre gearcase to confirm that they were in perfect working order. Photos were taken to document the condition of the low-hour components, and then the gearcase was resealed and filled with Mercury High Performance lower unit lube.
For our first series of runs, we used Mercury’s High Performance gear oil and achieved consistent top speed runs of 122.2 MPH and 106.0 MPH from the 2.5 and 3-litre-powered boats respectively. For accuracy, we performed multiple top-speed, long distance runs. After these runs, the boats were returned to the trailer and we removed the Mercury 90-weight gear oil. The gearcases were flushed the of any remaining Mercury High Performance oil prior to filling with Alisyn ProGear 21. Throughout our exhaustive testing, we ran both engines on ProPower 21 two-stroke lubricant mixed at a 32:1 ratio for the 2.5, and through the 300X's oil injection system.
Initial impressions of the Alisyn ProGear 21 Type 1 oil were that it’s thin – very thin. Could this thin oil provide just as much gear protection as traditional heavy-weight oils? We were on a mission to find out if Alisyn ProGear 21 Type 1 lived up to its claims.
With the 2.5 liter SportMaster flushed and filled with Alisyn ProGear 21 Type 1, driver Helmut Freitag had no problem achieving a best GPS-recorded top speed of 123.9 MPH. All speeds were consistently recorded in the 124-MPH range, indicating an instant gain of approximately 2 MPH – from an oil change. Additional extended runs were performed totaling several hours of high speed use and loading on the gearcase with no problems. Testing on the 3-litre SportMaster revealed a gain of .8 MPH and 50 RPM, which is impressive when one considers this is a heavier boating running at much less RPM than the 2.5-litre application. Also noted were increases in acceleration - a difference that became immediately apparent from the start of our testing.
Our prior concerns regarding the possibility that such thin oil would seep past the seals and enter the case were unfounded, as no evidence of any water intrusion was present. Although Alisyn ProGear 21 Type 1 is blended from a highly specialized additive formula, it is compatible with most seals, O-rings, and gaskets including plastic, elastomeric, and rubber. Also worth noting that ProGear is available in a variety of viscosities, all offering Alisyn's superior protection additives.
After testing, Molnar completed a full disassembly of the 2.5-liter gearcase and evaluated all internal components for added wear. We’re pleased to report that Alisyn ProGear 21 Type 1 provided full protection, with no visible or measurable signs of added wear.
In addition to ProGear's impressive performance, we're also pleased with ProPower 21 two-stroke oil. As we know, nothing tests an oil's integrity more than extreme high-RPM use over extended periods of time, and ProPower provided clean-burning protection. Removal of the cylinder heads for inspection as well as leakdown tests confirmed that there was no oil-related wear that occurred during our evaluation. We'll be using ProPower and ProGear lubricants for more extensive, long term tests with a follow-up report, but from our current findings, we're confident that Alisyn's products provide excellent high-RPM protection and performance.
For those of you looking to extract maximum performance from your performance boat, this product should be on your upgrade list – and unlike most modifications that will provide the potential for 50-200 RPM increases, this isn’t nearly as expensive. Results in this test are based our our testing, using Mercury SportMaster gearcases. Are our results of this evaluation representative of how your particular boat will benefit from using Alisyn ProGear 21? Possibly, but it's always best have a professional technician inspect your engine's components to evaluate their condition and suitability for your application. That said, our evaluation does prove an undeniable fact – this product lives up to its claims by freeing up power while providing full gearbox and engine component protection.
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