Originally Posted by Janster
With that many miles.....I would not go with synthetic.
Synthetics tend to act as cleaning agents and helps remove sludge (so to speak). Using synthetics now - may cause new leaks to develop.
I switched to synthetic on my 96 with 60K miles and I developed a leak down at the oil pan and a slight lifter tap after owning it a couple years.
this is a well spread myth, and is not true.
Synthetics do not create leaks, but will show a bad seal sooner than dino oil because the molecules in synthetic are smaller and will creep their way through an infant leak quicker than dino oil. There are no detergents in synthetic that will eat away at your seals. The seal was already going bad and the synthetic is just "pointing it out" quicker, it would eventually leak with dino oil too.
I switched to synthetic at 160k miles and have had no problems so far and I am at 175k miles.
OP: My recommendation is to start using synthetic, but whatever oil you use (dino or synthetic) make sure you change it at regular intervals and use a good paper air filter to keep your oil clean.
I believe 5w30 oil is what is recommended for our trucks.
Avoid fram and STP oil filters (Use OEM oil filters and air filters
, best option IMO)
My favorite dino oil is castrol, favorite synthetic is mobile 1 or castrol. And I either use a mobile1/K&N oil filter or an OEM toyota oil filter.