For my Hemi Ram I go to Walmart and buy the 5 quart jug and 2 one quart bottles of Mobil 1 full synthetic oil. I also buy the Fram extended guard (7000 miles) oil filter. I can do my oil changes using Mobil 1 for less than $40 and I am using a 6,000 mile interval. It costs me less to do my 7 quart Hemi Ram than it did to do my 5 quart Tbird because I change the oil less often.

 

What will happen if you go back to regular oil after switching to synthetic? I put in synthetic on my last oil change, but now I'm thinking its not really worth it.

 

What he said. Once you go synthetic you have to stay synthetic. Plus as your truck gets older it become more prone to oil leaks when using synthetic.

 

The whole leak think is not true. I switched a 100k mi Pontiac Firebird to synthetic and no leaks....ever. I work on a 700hp '93 stang with a '96 Cobra motor and 22 lbs of boost...We frequently switch from dino to synth for cam changes, test runs, ect...Never any problems.

You will just extend the change period, and, I have seen an increase in oil pressure using same weight switching to synth in the above car. Synthetic also holds up better to exotic fuels such as N20, forced induction, race gas, ect.

I won't use anything but Mobil1, and keep in miind to use the factory weight. 5w-20 for the Hemi.
Think about it, ATF+4 is synthetic trans fluid, the rearend fluid is factory filled synthetic. The new "long-life" antifreeze has synthetic additive to increase life of the fluid, reduce interval change and wear.

Bottom line, change at 3k like me, or 7k if you are a wuss on the pedal, spend the extra money on the synth...it's worth it.

But, what do I know.

 

but exactly what problems arise by going from synth back to dino? Everyone says it, but I've never heard it explained.

 

Can anyone answer why I can't go back to dino after switching to synth?

 

NO, they can't, there are NO adverse affects from switching...old wives' tale.

 

There are no bad effects from switching back to dino oil but its not the best to keep going back and forth. My question is why would you want to go back to it after using synth?

 

I do the same thing as far as buying at Walmart, but try to stay away from the Fram filters (which isn't easy because it's the most common one sold out there). If you do a search on oil filters you'll find a link in some past threads on filter studies. Fram consistently came out worst. Best rated were Mobil1, NAPA Gold and Wix.