[guinnessdood]

Got an answer back from Exxon Mobil regarding some testing they did on their M1-207 oil filter for us...

In response to the customer questioning the subject filter performance, I can offer the following comments. There are two avenues of leak back paths in the filter. One is leakage past the rubber anti-drainback valve (check valve) back thru the outer ring of inlet holes in the filter baseplate. Silicone rubber is used for this application and provides the ultimate material for long life in extreme temperature swings. The second path is the area between the baseplate and the sheet metal gasket retaining plate. Our manufacturing process applies a ring of sealant between these two components just prior to the components being spot welded together. Occasionally skips do occur while dispensing the adhesive ring due to air pockets in the pressurized dispensing system. A real world evaluation can only be made using the actual engine application in question, a Corvette with the ZR-1 engine option. We unfortunately do not have one available to test. Unknown conditions within the engine, such as bearing wear, bearing clearances, and pump wear and clearances make it impossible to duplicate the engine characteristics in the lab. To evaluate worst and best case performance, I had a sample filter made with no sealant between the base plate and gasket retaining plate, and a sample filter made with a perfect seal between these two components. The sample filters were actually made on the assembly line using production methods. Our lab, and our competitors, typically test anti-drainback performance using the SAE HS806-2001 test standard. For our testing of the sample filters, we used Mobil 10W30 oil in place of the specified mineral oil. The filter is placed inverted on a stand while an elevated 100 ml graduated glass Burette tube filled with Mobil 1 10W30 oil is "piped" into the filter outlet. Leakage is checked, from both pathways mentioned above, based on per hour time sequence. In the SAE test, the sample with no sealant leaked 470 ml (16 oz.) in one hour. The sample with perfect sealant had zero leakage. The following evaluation was made using the same two filters with non-typical test methods. The filters were flowed at 3 gpm on a test stand using Mobil 10W30 oil for one hour at 250 F. This conditions the internal components of the filter in an environment similar to that found in the engine. The filter was weighed full of oil after being removed from the test stand, the outlet plugged, and the filter was placed inverted (like the filter mounts in the ZR-1 engine) on a ring stand placed over a drip pan. The filter was re-weighed following eight hours and the leakage through the inlet holes (past the anti-drainback valve) was reported. The leakage of the filter with no sealant was 5 grams (0.2 oz.) while leakage of the perfect filter was 0.7 grams (0.02 oz.). The two filter samples were then re-filled, re-weighed, and a 1/8 inch diameter hole was made in the dome of the filter's shell. Repeating the same eight hour test method, the leakage of the worst case filter was 1081.5 grams (38.2 oz.) while leakage of the perfect filter was zero. Design and condition of the engine gallery and effective sealant application between the filter backplate and gasket retaining plate will affect filter drain-back leakage significantly. Any occurances of less than acceptable sealant application in Mobil filters should be considered an exception to the normal level of quality.