AMSOIL HP Marine vs Evinrude XD100: A Real Alternative for Your E-TEC?
Every E-TEC owner on the peninsula has had the same conversation at the counter: the engine was set up to run on Evinrude XD100, the dealer said nothing else would do, and a bottle of it costs more than the same amount of any other two-stroke oil on the shelf. BRP stopped building Evinrude outboards in 2020, so the fleet is only getting older and the oil bill is not getting smaller. We stock AMSOIL HP Marine as the alternative, and this guide is the evidence for why, rather than the sales pitch.
Why an E-TEC is fussy about oil
An E-TEC meters its own oil. The engine computer reads revs and throttle position and decides how much to inject, and it has two programs: the standard ratio it leaves the factory on, and a lean-mix setting that uses noticeably less. The lean setting is the one people want, because it is the one that makes the oil bill bearable, and it is the one with a catch. To have it switched on, an Evinrude dealer reprograms the engine and the owner agrees to run XD100 and nothing else. BRP never published a performance specification that another oil could be tested against to qualify for that setting. So the question of whether another oil is up to the job could only ever be answered one way: run it, pull the engine down, and look.
What HP Marine is
AMSOIL HP Marine is a full synthetic, TC-W3 rated injector oil built for direct-injection two-strokes running lean, which is exactly the E-TEC, the Mercury Optimax and the Tohatsu TLDI. It carries a heavy detergent package, which AMSOIL calls MAXDOSE, aimed at the ring sticking and exhaust-port carbon that lean-running direct-injection motors are prone to. It is low-smoke, and it passed the OECD fish and daphnia toxicity tests with full survival, which matters when the oil is going out the exhaust into Spencer Gulf. It can be run as injector oil or as a 50:1 premix in any outboard that asks for TC-W3, so the same bottle also serves the older Johnson, Yamaha or Mercury on the other trailer.
The test: two 250s, 534 hours, one teardown
AMSOIL ran a field study with Sea Tow, the marine assistance outfit in Naples, Florida, whose boats spend their working lives towing yachts and sports cruisers, which is about as hard as an outboard's life gets. The boat carried a pair of Evinrude E-TEC 250s. Both ran 28 hours on the standard setting, then an Evinrude dealer reprogrammed both to lean mix. The starboard engine's reservoir was filled with HP Marine and the port engine's with XD100, and they ran side by side for 534 hours, roughly 240 of them under tow. At the end both engines were stripped and rated by a calibrated ASTM rater against the NMMA TC-W3 criteria, using the Coordinating Research Council's deposit-rating manual. Ten is a part with no defects, and the percentage figures are the share of a surface showing a fault. The testing ran from February 2009 to April 2010, and the results describe the oils as they were formulated then.
What the parts showed
The short version is that the two engines came apart looking like each other. Here is the long version, because it is the long version that should decide what goes in your reservoir.
Piston skirts. Varnish rated 8.52 on HP Marine and 8.57 on XD100. Skirt scratching, the fine linear marks left by particles in the oil and air, measured 1.42 per cent against 1.25 per cent. Scuffing, the matte damage that appears when an oil film gives up, was zero on both engines.
Rings and lands. Top and second rings scored a perfect 10.00 for sticking and deposits on both oils, which is the number that matters most in a two-stroke, since a stuck ring is lost compression and, eventually, a lost piston. Crown land deposits were 3.98 for HP Marine and 2.99 for XD100; second land deposits went the other way, 5.91 and 6.82.
Piston crowns. This is where the two oils separated most. Crown deposits, the ones that cause pre-ignition and the poor running that follows, rated 7.02 on HP Marine and 6.31 on XD100, and the photographs show it: the HP Marine crowns are a fairly even dark grey, while the XD100 crowns carry the heavier tan build-up. Undercrowns were 2.18 and 2.66, and undercrown deposits do not affect how the engine runs.
Cylinder heads. Head deposits rated 8.76 on HP Marine against 8.14 on XD100, both comfortably clean.
Cylinders and exhaust ports. Port blocking, the carbon that chokes a two-stroke's breathing, was 1.08 per cent and 1.17 per cent, and port deposits rated 9.89 and 9.88. Bore scuffing was zero on both, and the cross-hatch from the factory hone was still visible in every cylinder of both engines after 534 hours.
Bearings and crank. Crankpin rod bearings rated 9.90 and 9.88, wristpin bearings 8.38 and 7.62, and the wristpins themselves 6.82 and 6.38. The bearing races in the rods were within a few hundredths of each other. The crankshafts rated identically, 9.85 on the crankpins and 9.78 on the main journals, and the main bearings came out at 9.95 for HP Marine and 9.89 for XD100, with trace to light wear and next to no deposits on either.
What that means in practice
Read fairly, the study is a draw, with HP Marine a touch ahead on the deposit measures that affect running, the crowns, the head and the wristpin bearings, and XD100 a touch ahead on second-land deposits and skirt scratching, none of it by a margin a mechanic would pick with the engine on the bench. What matters is the floor: no scuffing, no ring sticking and no port blocking to speak of, on an oil that was not the one the lean-mix program was written around. On the strength of that, AMSOIL states that it fully supports HP Marine as a replacement for XD100 in E-TEC engines and covers that use under its own limited warranty, document G1363. That is the maker of the oil putting its name to the application, which is an assurance BRP never offered for anything but XD100.
Two honest caveats. It is AMSOIL's study of AMSOIL's oil, with one engine on each oil; that is how teardown comparisons are done, because nobody strips a dozen 250s, but it is still one boat. And it was run on the oils as blended in 2009 and 2010. Neither changes the conclusion, because the question the study set out to answer, whether a lean-mix E-TEC is safe on this oil, is answered by the parts.
Switching over
HP Marine is compatible with other TC-W3 oils, mineral or synthetic, so there is no need to drain the reservoir. Run it down, refill with HP Marine and carry on, keeping the mixing to that one changeover rather than alternating bottle by bottle. Nothing about the engine's programming changes, whichever setting it is on. If the low-oil light or the oil consumption has ever seemed odd, sort that first, since no oil can make up for a metering fault; our E-TEC servicing and diagnostics guide covers what to look at.
For sizes, the 946 mL bottle suits topping up through a season, the 3.78 litre jug is the economical way to keep a lean-mix 250 fed, and there is a carton of four jugs and a 208 litre drum for operators. The whole AMSOIL range ships Australia-wide from Kadina. If you want to talk it through against your own engine and the way it is programmed, ring 0412 532 984.