My daily driver is a 79 Subaru DL with an EA71S engine swapped in. That is a 1.6l flat 4, pushrod engine, high compression (12:1-13:1ish), low tension rings, naturally aspirated, gear drive cam, long cam duration (around 305/305 advertised). Powerband is around 4000-6700 RPM, cruising RPM is around 3500-4000 usually. Does not have an oil cooler, and has large bearing clearances. Oil temp tends to run at around 102C on the highway, but can reach as high as 130C. Likes a 50 or 60wt oil. Driven 90-95% highway, long distances. In winter I tend to run M1 FS X2 5W50. Mainly because it's easy to find. Does well for cold starts but seems to start shearing or getting thin at around 3000mi. By 5000 it is no longer usable in this engine and has to be changed (hot oil pressure too low). Been thinking about trying another oil. Molygen 5W50 looks attractive but not sure if it will really perform any better than the M1. The Kohler 10W50 small engine oil is also easy to find at Tractor Supply and has good specs. Ravenol makes a 10W50, so does HPL, and there are various motorcycle 10w50s and thin 15w50s. HPL and Amsoil also have 5W50s. There is also the ZO6 Corvette 5W50, M1 Supercar. What do you guys think will perform the best, while also not being outrageously difficult to find. Here are some spec sheets:
From these data sheets, the 10W50 Kohler Pro oil looks surprisingly good, especially for how easily available it is. The NOACK is quite low, the HTHS looks good, although the KV100 is a bit low. The Molygen is reasonably priced, has a high KV100, but has a high NOACK and unknown HTHS. Ravenol RSE has a great HTHS, good NOACK, and decent KV100, but is hard to find. Same with RRS but specs not quite as good. Both the HPL 10W50 and 5W50 look excellent, just have to be special ordered. Maybe if they have good shipping I would be willing to go that route. The Amsoil 5W50 also looks attractive, and NAPA right down the street is an Amsoil dealer. The Motorex oils look downright amazing with NOACK<6, and are not all that hard to find (KTM dealer). No HTHS or NOACK listed for Mobil 1 Supercar 5W50.
From these data sheets, the 10W50 Kohler Pro oil looks surprisingly good, especially for how easily available it is. The NOACK is quite low, the HTHS looks good, although the KV100 is a bit low. The Molygen is reasonably priced, has a high KV100, but has a high NOACK and unknown HTHS. Ravenol RSE has a great HTHS, good NOACK, and decent KV100, but is hard to find. Same with RRS but specs not quite as good. Both the HPL 10W50 and 5W50 look excellent, just have to be special ordered. Maybe if they have good shipping I would be willing to go that route. The Amsoil 5W50 also looks attractive, and NAPA right down the street is an Amsoil dealer. The Motorex oils look downright amazing with NOACK<6, and are not all that hard to find (KTM dealer). No HTHS or NOACK listed for Mobil 1 Supercar 5W50.