I have been running the FL1-HPs on my Plymouth for awhile and have purchased Wix filters because of cost,I have 51515 and 51515R filters. I know the microns and flow rates are different between the two, but I'm looking for some input.
My car usually gets an oil change once a year. I doubt I put more than 300 street miles on it and maybe 30-40 passes down the track a year.

Street driven, I'd run 51515.

I'd go with the 51515 (lowest microns-20 iirc) for the best filtering.

I've always used the normal 51515.

The 51515R is the racing filter and it flows
more but doent have the filtration of the 51515
which I use all the time now

Thanks Guys!
The 51515 has a burst pressure of 290#, so cold start ups at 90# shouldn't be an issue.

I use the 51515xp on my street car/ n/ss car. it has a thicker case. but the same filtration as a regular 51515.

51515

Although I have yet to take advantage of it, I just came across the Wix filter discount thread linked below. Since you posted up a Wix discussion, I figured I would bring it up for other members like myself who may be unaware of the savings potential. Certainly worth taking a look at if you already haven't.
-Trent

WIX Discount for Moparts Members - Link

That discount works great, although its been about 6 or so months since Ive used it.

When I was looking for the 51515 I had a tough time finding them. I went to Carquest and the guy said Carquest filters are re-branded Wix and the 51515 is part of the Carquest p/n.

Napa gold 1515 is also a wix. Been using those on the roadrunner.

Rock Auto $4.06

I've had at least 4 bad wix filters in the past few years... so check your oil pressure when you put one on and be ready to turn the engine off fast.

I always crank til I get oil pressure,before turning on the fuel.

For a street motor where reliability is excelent due to the parts used, i would go 51515. Race, 51515r to catch debris should you have a failure and metal floting around. With the higher flowing media, the r filter doesn't bypass the oil nearly as quickly, lncreasing the chance to catch the junk.

of the 30+ years i have ran wix filters, i have had several where the threads were bad. i have a 3/4-16 "form" tap which, as the name suggests, "roll forms" the threads with no metal removal. those i have fixed easily, and i have a plated 3/4-16 bolt i use to check the threads on every filter i use because i fill each filter before installation. the only other defect i have come across using these filters is once in a while, for whatever reason, the filter comes without a gasket. those, i return. the 51515 fits my whole fleet, including my FWD minivan with the 3.3 engine, so i buy these by the case.