I doubt that it matters but I'm surprised about the
'not for water cooled engines' part. The TCW-3 rating is by the BIA
(Boating Industry of America). I haven't seen an air cooled boat motor in
a very long time.
Actually I didn’t intend to imply ‘not
for water cooled engines’. I said ‘watercraft’ and
meant to say ‘personal watercraft (PWC). And, also, it seems I got
confused. The TCW3 rating is a NMMA rating (National Marine Manufacturers
Association). I had read a long
article I came across http://www.sea-doo.net/techarticles/oil/oil.htm,
and got mixed up on the NMMA TWC3 rating and the API-TC (American Petroleum
Institute) rating. (And if you read the article only once in its entirety,
you may be able to see why I got confused.)
For PWCs the author is suggesting
sticking with API-TC rating which is less common and more expensive than oils that
are TWC3 rated. And after re-reading, my conclusion is that the TWC3 oils
should be fine for a water cooled rotary. Some highlights are given
below.
What mix ratio are you guys using?
Al
“Ashless detergents
are used in low temperature applications such as TCW3 oils where the ring land
temperature is held below 300 deg/f. These detergents work well in engines
where an excess of cooling capacity is available and power valves are not used.
Ashless detergents are manufactured form organic nitrogen compounds (Hydrazine)
instead of heavy metal compounds; therefore, they produce no ash as they are
burned away. This is where the name “Ashless” comes from. Oils
containing this type detergent have a characteristic Ammonia odor. Ashless
detergents were used in the first generation of Bombardier XPS engine oil. The
formulation was later changed to a low ash type detergent because of the higher
temperatures generated by the 787 engines.
Low Ash type detergent/dispersants are used in most API-TC, Jasco FC
and ISO GC certified 2-stroke oils. These oils are designed for air-cooled high
performance engines that operate under severe load/temperature conditions. Low
Ash detergents can keep the deposits to a minimum at ring land temperatures as
high as 400 deg/f. These detergents are manufactured from compounds of Calcium
and Magnesium (heavy metals). After these compounds (Calcium Phenate or
Magnesium Phenate) do their job, they burn away, forming a heavy metal salt
(ash) that is swept away during the normal combustion process. Hence, this is
where the name Ash-type detergent comes from. Ash type detergents depend on the
higher combustion temperatures (787 and 951 engines) to keep the resulting ash
swept out. Therefore, the use of these high performance oils in outboard or
other mildly tuned 2-stroke engines is not recommended.
Some manufacturers are using a combination of detergent types (Ashless and Low Ash) to provide a broader range of uses for
their oil. It is important to note that oil designed to meet TCW3 specs. only
(Ashless) will not protect an engine requiring API-TC (Low Ash) type oil. The
converse is also true. Using a Low Ash oil in an
engine designed for an Ashless type oil only could result in fouled plugs and
gummy combustion chambers.
I hear a lot of complaints about the high cost of some 2-stroke engine
oils, mostly Bombardier XPS. Well, I have to agree, it isn’t cheap, but
neither are any of the other API-TC oils compared to the TCW3 type oils.
Unfortunately it just costs more to manufacture API-TC oils than TCW3 oils.
Despite its relatively high cost, I cannot recall any Rotax engine failing
because of XPS oil. XPS oil was a joint development of Castrol and
Bombardier. Bombardier wanted a ‘universal’
high performance engine oil that they could use in all their recreational
products. That meant oil would flow freely at –40 deg/f and still
maintain sufficient film strength at 350 deg/f. The first generation of XPS
(1995) was formulated using Ashless detergents; this allowed the Rave valves in
the then new 787 motor to stick. The formula was later changed (1996) to a low
ash detergent that eliminated the rave valve sticking problems. There have been
several minor improvements in XPS since 1996. Castrol remains the only
manufacturer of XPS. This is a proprietary blend sold only by Bombardier. There
are a number of good API-TC type oils out there if you chose not to use XPS. If
the oil you want to use does not have the ATP-TC certification on the
container, contact the manufacturer. Most of them will be more than glad to
provide you with information on their products.
Do not use TCW3 in your SeaDoo PWC. I don’t care if
it’s a full synthetic or your brother-in-law uses it; for the reasons
stated above, it will not protect your motor when conditions get tough in your
motor.