Engine oil thickens at cold temperatures, this thickening is commonly referred to as congealing. Even though it is bolted to a warm engine, it is possible for a congealing type oil cooler to remain cold enough to cause the engine oil inside it to remain cold and thick (congealed). When the engine warms up to about 160-180F the vernatherm directs oil into the oil cooler, but if there is congealed oil in the cooler, it can take a considerable amount of time for the oil to begin to flow through the oil cooler.
To avoid this situation, Non-Congealing oil coolers were designed to have a small - but continuous - amount of engine oil flowing through them at all times - even when the vernatherm is in full oil cooler by-pass mode at low oil temps. Non-Congealing oil coolers feature what is (non-technically) referred to as a "Wee-Wee Hole" (as in the picture above, right). This "Wee-Wee Hole" is a passageway running through the center of the oil cooler, through which a constant supply warm engine oil is pumped. This keeps the oil cooler - and the roughly two quarts of oil it contains, at (or near) the temperature of the engine. This way, engine oil can easily flow through the oil cooler the very instant that its flow is directed there via the vernatherm.
Under "Model Differences" are Oil Coolers commonly used on your aircraft. The part numbers of the baffles that fit each oil cooler are listed. Please measure your oil cooler to determine the baffle package that fits your aircraft.
A congealing or non-congealing oil cooler can be identified by the thickness of the base plate and the presence of the "wee-wee hole" as indicated in the pictures below.
12 Bolt Non-Congealing Oil Cooler
12 Bolt Congealing Oil Cooler
Bare aluminum finish
6061-T6 aluminum with black high-temperature fiberglass reinforced silicone seals pre-installed