UPDATE
I had the rear diff fluid changed last week using 80w 90 Walmart SuperTech conventional with a FelPro gasket @ 75,000. Mechanic said everything looked okay and that it looked like it was never changed before.
I forgot to mention that after purchase, my car developed a periodic howling...
Thanks. They're a bit more expensive than the Crossmax tires with the same 98 load rating and 80 less tread ware at 520 versus 600 for the Crossmax. Out of curiosity does either or both of your 2011 Grand Marquis UE and 03 Marauder require an additive for the rear diff fluid?
With price in mind, the Hankook Kinergy has comparatively impressive stats. Will check the others on your list. Mavis and some other tire shops are good when it comes to matching lower prices elsewhere.
STP makes a conventional 80w 90 without and modifier for LSD. The Walmart Supertech 80w 90 is a conventional with the added modifier.
At issue is what's better 75w 90 full synthetic or 80w 90 conventional?
Thanks. Are you able to tell if it needs the rear diff fluid additive? I'll ck to see if the prior owner answered the aforementioned safety recall. At some point I'll replace the existing lenses and go to LED.
Re: 2004 Grand Marquis LS Rear Differential Fluid, ATF...
Recently bought the above referenced car at just under 69,000 miles. Manual says 80w90 for rear diff fluid. Numerous sources say it's okay to use a synthetic 75w 90, taking about two and a half quarts.
I'm near certain my car doesn't...