Here's my extry peso, for what it's worth.
All of the previous posts are valid. Dan, I'd be careful on making an opinion on your one experience; as you said, it could have happened anyway with non-syns. And with tranny and axle fluids, the synthetic concept either works or it doesn't and it's no different for the rest of the moving metal parts wearing in the engine.
I'm like you; had great results with non-syns, but I am willing to defer to the "new oil age" if all of these great advantages keep proving themselves while using synthetics. I'm getting another mile+ mpg with synthetics in my Explorer. That's telling me there is less friction going on somewhere under the hood which means less wear and also less excursions with a wrench to fix them when this powerplant starts racking up the hours/miles on my vehicle. Time will tell. I'm an "old phart" now and I have more patience to wait and figure this out. I have confidence that none of us will really be losers in the end anyway. I would never trade these piddling arrow-splitting issues to the times when we really HAD to change oil that frequently, adjust the points and condensor, and were happy to get over "65k miles" from our vehicle (which amazingly seems to be the exact same mileage that all older/classic cars have here when offered for sale).
OK, back to the subject. Don't start your new engine with synthetic, but if you can afford the extra cost of the "insurance" it provides, use it after break-in at 10k mi or so.
Stick with high quality.
I have always changed my oil religiously at 4,000 (not 3,000) miles. I used a high quality oil, always Castrol GTX or Pennzoil, nothing else. I tore down my air-cooled Kawaksaki 1000 motorcycle at 80,000 miles and there was no evidence of any excess wear except a little blow-by fingerprint on the cylinder walls which I could contribute to a one-day thousand mile ride that included 85 mph driving through Arizona when the temperature under the shade was over 120+. My old Honda CRX auto is parked out back now but still runs strong and doesn't burn oil at way over a quarter million miles. Neither of these vehicles ever tasted synthetic oil and the non-synthetic quality we get now is even better.
I now use Mobil One or Castrol synthetic in my Explorer and change every 5,000 mi instead of 4, so I "recoup" a little of the added cost.
Now about that oil filter. I too wish I could find that link again. It was a great study on filters that some guy did and it changed what I use. I had what I would describe as a lifter tick on my new '99 SOHC at startup and worried about if the timing chain tensioner problem applied to me. Then I read that link describing how the ubiquitous orange Fram oil filter that everyone uses has an internal valve failure in its ability to hold oil up in the engine and lets it pass through the filter down to the pan on shutdown. Thus a symptom is a tick immediately at startup until new oil gets back up into the engine. I crawled under my Explorer and dang if I hadn't taken all the trouble to put in $5/qt synthetic oil and then stuck one of those cheapo orange filters on my SUV. The next weekend I switched filters to a better Castrol Plus something-or-other $5 filter and my tick immediately went away. Now I don't worry about a major timing chain tensioner problem (yet).
Brandon, while you may be right to question to motives of the report you got, the fact remains that the other study still rated the Purolator filter more highly. Who knows, I'm not saying that other report doesn't have an agenda we don't know about yet, but at least it's a second opinion.
Just food for thought. The filter makes a difference too. Don't pay all that attention to your oil and forget the filter. The same study said nothing beats the Mobil One filter: it is the best. Maybe it really is worth $10. I'm thinking of using it next time and changing it every other oil change.
Tony, one other thing. There was another great link to oils that I think we lost when the "Modified Explorations" forum blew up. I can't remember the exact justification for the resulting opinion, but it discusses the extreme weight range available in synthetics such as the 5w-50 you mentioned. With non-synthetics, it just isn't possible to get that extreme of a range in temperature-oil weight ability.
I can't support what I am about to say (hopefully someone can lead us to the link again) but here goes. First, you're getting back a newly rebuilt engine that doesn't need 50w oil: 5w-30 is recommended by Ford and unless your rebuild shop screws up your engine, why put 50w in it? That's for air-cooled engines with large variances in cylinder wall tolerances / clearances through different operating environments (or sick auto engines that burn oil).
Secondly, that article discussed the chemical characteristics of the amount of polymers formulated into the synthetic blend that is required to acheive that large level of universal weight range and determined that was enough of an excess to actually degrade the protective abilities of the oil. In other words, when you see an oil with a weight range like 5w-50 it has so many polymer chains in it too acheive that rating that the other lubricative properties are actually hampered.
Someone help me here if they can remember or explain this. I'm no expert, but I remember after reading that study I'd never buy 5w-50...
PART TWO/ post cont'
Tony,
Well, now I finished preaching, so here's my SPECIFIC answer to your ORIGINAL QUESTION and I defy anyone to beat it! You asked directly what is the best to do. Here's what you need to do:
You are getting back a new rebuilt engine. Do NOT put any synthetic (or synthetic blend either) for the first approx. 10k miles. You mentioned Castrol so you must be a Castrol fan; that's fine since they have great oils.
1) Burn Castrol GTX non-synthetic for two or three oil changes at 3-4k miles each. Use the 5w-30 (or 10w-30) recommmended by Ford unless you have extreme reasons to change it because you have different habits from all of the rest of the thousands of us driving Explorers.
2) Purolator PureOne is their upgrade oil filter and will work fine. Don't buy a cheapo.
3) Afterwards use Castrol's synthetic (or Mobil One) for the next quarter-million miles. You can change it every 5k miles instead of 3k to recoup some of the cost and still get all of the life out of your engine: that's part of why synthetics are supposed to be better.
4) Don't buy the cheapo filter. And it shouldn't cost that more. Unless anyone can argue with me with real data, I'll bet my ex-wife that you can drop the big bucks on a $10 Mobile One (there-ain't-no-better-filter-made type) and just change it every other oil change to help mitigate the cost of it and still drive an Explorer engine into mileage that requires a new digit capacity on your calculator.
There you go. End of discussion. Dead Link Removed
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Gerald
'99 EB 4x4
K&N / Drilled Airbox
Torsion Twist / Shackle Lift
Zaino, Wood Dash, CB, and Millenium Jack Antenna Ball Dead Link Removed
