88351-S8 studs are Loctited in, but I felt like I was rollin' the dice. 

Mark.  If you are not leaking any oil, then it would be advisable to just leave the two bolts in place.  Sealer on the bolts when they are installed in the rear seal retainer can prevent the aforementioned oil leaks in that area.  From the factory, there were two studs installed in the rear main seal retainer to eliminate the possibility of any oil seeping past the threads.

I get a large number of core engines missing those studs which is the first indication that the engine has been into after leaving the factory.  The Mr Gasket #59 stud kit is what I use when I do not have the actual original Ford studs to use.  Because these studs do not have an ‘interference’ type of thread, some Loctite is required which also helps to seal the threads.  While they are longer than the original studs, the extra length is not a problem.

Studs when properly installed along with some type of sealer will prevent oil from seeping past the threads in the rear main seal retainer.  Using bolts rather than studs in the rear main seal retainer does increase the risk of an oil leak in that area and expecially if no sealer is being used.  Any oil making its way past those particular threads will look like a rear main seal leak and that could end up being a considerable amount of work being performed that is not actually addressing the root cause of the oil leak.

Lorena, Texas (South of Waco)

OK Thanks. Makes sense but I don't think the Bolts in mine were leaking. I may try and locate some Studs.

  

I believe it's best to use studs as opposed to hex head bolts in that application. The seal retainer is aluminum, much softer than cast iron and those threaded holes enter the interior of the engine where lots of oil is thrown around. Therefore the studs must be installed with a very good thread sealer when all is clean and never disturbed after being screwed in. Simply remove/replace the nuts when dealing with the oil pan. That would avoid leaks and possibly stripping or wearing out the threads in soft aluminum either from over torquing as an attempt to stop it from leaking or from repeated use. Just my 2 cents worth....

64F100 57FAIRLANE500

Same Question  I asked in My Post. Why are Studs used in this situation. Took mine apart. No Studs just regular Pan Bolts.

  

Ted confirmed that the 5/16-18 end of the 88351-S8 stud has "prevailing threads." To install it in the cap, it has to be double-nutted; it can't be screwed in with your fingers. I had never heard of "prevailing threads." Ted continued to say when the 88351-S8 stud is not available, he has used a Moroso stud with an OAL of 1 3/8; the extra length, apparently, isn't a problem. With either stud, he recommends using Loctite Blue or equivalent on the cap end to prevent an oil leak. 

Am I missing Something about these Studs?  I took mine apart and there are Bolts holding Pan to Seal Retainer.  What is the Purpose of having Studs instead of regular Pan Bolts? 

  

The 88351-S8 studs arrived yesterday, but they don't fit. Although the OAL of 7/8 is correct, I think the zinc plating is preventing them from being screwed into the retainer. I double checked them by attempting to put a 5/16-18 nut on, but wouldn't work. The Dorman studs that I had previously bought fit the retainer, but they are 3/8 longer at 1   1/4. I will use the Dorman studs and hope that the extra length won't be a problem. 

I sent an email to Hill's, requested a refund, and told them to check their stock before fulfilling any more orders for the studs. 

Here is a quote from Hill's: "We went and talked with the lead mechanic/tech on the restoration side. He told us that the side that goes into the cap will not finger tighten, you have to use a tool to tighten them into the cap. I believe [they] have prevailing type threads so they cannot rattle back out. I tried a 5/16-18 nut and it was the same as the cap." Of course, I'm concerned about trying to install a steel stud into an aluminum retainer cap. I've experienced enough stripped threads for one lifetime.                                                                                                                              

88351-S8 is the correct part number for the studs. Tim Hill said that they weren't included in their catalog/website due to low demand, but both will be updated. NPD has them, same part number. 

____________________________