97 Explorer oil advice?

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Jan 17, 2003
Milwaukee, WI
I just bought a Ford Explorer from a co-worker, it's a 1997 w/4.0 SOHC and 70K in really good condition.
It's been well taken care and fed Mobil 1 5w-30 since 5K, changed every 5K like clockwork.
I'd really like to keep using Mobil 1 but due to my current stock pile (must be a sickness...but who can pass up a good sale on oil?) of Pennzoil and Chevron I'm going back to dino.
Question is with this SOHC engine which weight would be better for a daily driver. I put on 40 miles a day, 30 of which is freeway.

Stay with 5w-30 or go to 10w-30 or doesn't it really matter?
I believe whatever I use 4K OCI is about right for dino.

any thoughts?
If it's been fed a diet of the M1 since birth, I would really hate to switch to a dino now. The dino juice will varnish the insides some. Now others on here don't get a hissy fit over that statement. All I'm saying is that the dino will stain a little more so than what M1 would and since it was being used since birth, there WILL be a noticable difference. Also I would not go to a 5W-20, that weight has specifically been listed by Ford as one not to use on the 4.0 engine.
Keep using M1 and stretch the interval, this Summer if required.

You can always have a yard sale.
For your '97 I think your V6 is the older OHV not the SOHC V6. I don't think the 4.0L SOHC went into the Explorer until 2000. Anyway since the previous owner has been using Mobil 1 5W-30 I would spend the "few extra bucks" and continue using the Mobil 1. You'll pretty much insure that your engine will stay clean for many, many, many more miles
. My wife had a 1996 Explorer with the same engine and she had the oil changed every 5,000 miles with whatever dino oil her mechanic was using at that time. I saw some of the receipts and the oil used was sometimes 5W-30 and sometimes 10W-30. She sold the Explorer(her biggest mistake
) at 127,000 miles and it still ran like a champ. Though I never looked under the valve covers for sludge build up because there was no need to.

Her 1996 Explorer was totally trouble free for it's 127,000 miles. Her bought new 2002 Explorer has been a very expensive POS

Actually 97 was the first year that the SOHC was offered, although most Explorers were sold with the OHC until 2001, when it was discontinued. I have one of the last of the OHV's in my 2000 Explorer.

Roadking, I'm one of those (probably the minority) that says to go ahead and use the dino. It'll work fine in this engine. I use 10W-30 Castrol GTX in mine, with 4K changes. IMHO, a fine patina of varnish is not a negative. It will protect exposed metal from corrosion, and causes no harm whatsoever in an engine.

As was stated, stay away from the ligher weights with this engine; use only 5W or 10W-30.
Slight coat of varnish may not harm the engine, but what is it we all talk about here? Clean engines. Why even take a chance on getting some varnish on the engine when it's already clean?
Why switch from a good extended interval oil like M1 to go with dino? I would use the dino juice somewhere else and run the M1 6 months 7500 miles. Use 10w30 m1!

Daily Drives:
-2003 Toyota Tacoma PreRunner XtraCab, 2.7 Liter , Mobil1 Synthetic SS 5W-30.
ODO 8800 Miles.
-1995 Toyota 4-Runner 3.0 V6, Mobil1 Synthetic SS 10W-30.
ODO 85500 Miles.
Funny thing is the engine (SOHC) has a patina to it now. I know the previous owner did M1 changes religiously. I have all the paperwork and know the background.
I have a Taurus with 93K that I've only used dino oil on that is spotless as far as I can see...go figure.
That's why I was wondering if the Explorer engine with the overhead cam is harder on oil?
The only problem I have found with the patina in engines is when you have to slide something past it. For instance, if you want to change out the valve skirts or remove the valves from the heads, you may have a bit of difficulty getting them past the buildup. A scotchbrite pad and elbow grease seems to do the trick on removing the stuff. I've got a 93 F150 with 300,000 miles on it using Castrol GTX 10W30. Just finished a top end R&R due to an unrelated problem. I'm switching to Delvac 15W40 just because I think it's time, not because of any problems, and really mainly because I was recently diagnosed with the BITOG syndrome.
I have put a lot of miles on engines using dino with no problem. I say use a good dino with reasonable drain intervals and drive the crap out of it. I know its our nature in this group to really care for our motors, but remember lots of engines go a long time without synthetic oil and religious maintenence routines so I think you're safe.
Ford here uses Chevron Supreme 5W-30 in all of the gasoline engines, and I have it in my 97 Ranger with 200,000 km, 7,000 km changes, less than 4 mm down on the dip stick at changes.
These engines do not like thicker oil. I know one person who put a straight 40 wt oil in his at the first 2 changes and it made noises and started consuming oil. Started using the 5W-30 at 10,000 km and it consumed a qt every 3000. I switched him to 15W-40 and reduced the consumption to 1 qt in 6,000.
My wife drives a 97 Explorer with the 4.0 L SOHC that we got in 99 with 29K miles. We were the second owners, a funeral home had it first. It now has about 118K miles. I ran M1 10W-30 until 62K miles then switched to Castrol GTX 5W-30 because I began to notice a slight oil weepage around a few gaskets. The weeping went away almost immediately. The truck never has used any oil at all, to this day, and runs like a top. Oil changes are done at 3K intervals.

Changing the oil on this thing is a mixed blessing. It has enough ground clearance that I do not need to jack it up, but the oil stream coming out of the drainhole is directed at a frame crossmember and makes a mess. I bent a piece of sheetmetal into a channel about 12" long to intercept and direct the waste stream where I want it.

FWIW, I changed the front and rear diff lubes and transfer case lube to M1 products at 32K miles. Still in there with no problems.

This engine had a lot of newsgroup traffic about 3 or 4 years ago because of a problem with the cam chain tensioner mechanism. As I recall, it is a hydraulically actuated device similar to a hydraulic lifter in operation. When it is not functioning properly there is a tremendous clatter at startup. Ford denied the problem for a long time, then finally consented and did a recall. Make sure yours has been upgraded to the newest design.

Change your shocks if they have not been done yet. The difference is remarkable. If it is a 4 door, there is a fifth shock mounted transversly to the rear axle as well. You can do this one too for another $25 or so.

When you change plugs do it through the wheel wells and it is easy. Remove the tire assembly and the rubber inner fenderwell flap and the plugs are right there in front of you.

This has been a good vehicle for us, but I would like it more if it got better gas mileage. It routinely gets between 16-18 MPG with her driving, and up to 20 with me driving.

Good luck
What A Forum,
What a coincidence.
I really like this vehicle and only have been driving it for about two months now. I did notice how it leaned around corners and had a unstable feeling. I just replaced the shocks last weekend...what an incredible difference it made. I'll have to check into the shock mounted on the rear differential...I saw it but haven't replaced it.
I just changed the oil last night, I'm going with the Pennzoil 10w-30. I'll agree that getting under the vehicle is easy but the stream of oil needed to be redirected with the help of a used paper towel cardboard center...works well. From all I read about this SOHC engine it seems pretty easy on oil and with 3-4K OCI I think the dino juice will do fine.
The person who owned the vehicle before me was meticulous with the maintenance. I was reading all the receipts he gave and the plugs were changed at 55K and the recall for the intake o-ring leak was taken care of. I don't see anything about the cam chain...just the cam tensioner.
Thanks for the advice.
Roadking, I'm sure the reference to the "cam tensioner" is meant to be the "cam chain tensioner". It sounds like yours has already been done.

If you're interested in better handling, check out the rear anti-sway bar that ExplorerExpress offers. You'll only need the rear one since your 97 already has the thicker front bar. It made a huge difference in the way my 00 Sport handles.

FWIW, I have been running Mobil 1 10W30 or Amsoil ATM (depending on whay I have on hand) in my daughters 98 Explorer (same engine) for some time now and we have 0 volatility and no oil loss whatsover.

It has the same engine and 113,000 miles.
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