Oil Recommendations

I recently bought my first Jeep, a 1991 XJ Sport w/4.0L and 5 speed. I can't believe how much fun it it is to drive! I have a terrible time turning the engine off each morning at work!

My question is about engine oil. Is anyone running the synthetic lubricants such as Mobil1 or Amsol? I want this engine to last as long as possible and I am willing to spend more upfront to save later.

Thanks,
Tom

200K + on regualr old Penzoil....it does not matter really what you use, change it and filter every 3mo/3K miles.

Rev

I have an '88 with 236,000 on the original engine. I went for the first 175,000 or so using Pennzoil 10W40, Purolator filters, and changing every 2500 miles. Since Pennzoil merged with Quaker State I became concerned about product quality, so I changed to synthetic. I ran Mobil-1 10W30 for awhile but didn't get the oil pressure I expected. I now run Castrol Syntec 5W50 and change every 5000 miles.

I'm one of the synthetic users, I have been using synthetic in my last 4 vehicles. Prior to that I used regular oil, changed it as needed. When my 82 S-10 with it's 2.8L started leaking oil around 650,000mi I pulled both valve covers and the intake manifold. The sludge that was in there shocked me. I did the oil and filter on it every 3,000mi and this truck was my service vehicle that spent 95% of it's time on the interstates. I started using syn in my 87 Trooper II, at 150,000mi I pulled the valve cover and the valve train area looked like new, no sludge or crud in there at all. My wifes olds warped a head from overheating last month at around 140,000 so I had a new engine installed but I saw what the valve train area looked like when they pulled it and removed the covers to use on the new engine, again the valve train area was immaculate. I'm assuming from the area I can see on my 98XJ's 4.0 thru the oil fill hole that it is pretty much in the same conditon, clean.
Some things to watch out for when changing to synthetic, the synthetic will start to clean out any sludge in there, initally you will have to keep an eye on the oil and how dirty it gets, if you can't read the dipstick thru the oil you need to change the filter. As the sludge gets moved out it will start to clog the filter, you may develop some leaks that the sludge was blocking dried out gaskets so watch for that. Generally around the valve cover, oil filter mount, rear seal. One comment, if it looks like a rear seal do the valve cover first, they tend to leak in the back and do an excellent impersonation of a rear seal.
Initially I would use the mopar filters, the K&N and Mobil-1 filters are too expensive for the initial use as you will be changing the filters at least 2x between oil changes. Sometimes the parts desk will give you a pretty good break on a case of mopar filters. Personally I have noticed that either the AC or Purolators take about 5 seconds to supply pressure to the system, the mopars, K&N and Mobil-1's don't. When you change the filter you will also need to add a quart, a quart of regular dino oil won't hurt it and neither will running a 50/50 mix of syn/dino oil. Stay away from the premixed blends, they are not 50/50.
You said it's a 91, how many miles are on it ??

Oil Recommendations Reply

Thank you all for the replies to my initial post.

RichP,
The vehicle has 162+ Arizona miles. Some of these are offroad miles but most are highway. So far most of my driving is around town and back and forth to work. The daily use is only about 5miles per trip.

Tom

Even in Arizona, 5 miles is hardly enough to warm it up. I'd recommend that you stay with conventional oil in a good brand (Castrol, or perhaps Valvoline), 10W40 weight if you can get it, and change oil and filter every 2500 miles.

TT,

When I graduated from College in the Mid 80s I had one of my Mechanical Engineering Professors tell me to run 10W-40 in my new 86 Mustang. He taught Internal combustion Engines and his experience that was the best weight to run.

In the mean time the whole car industry has switched to 10W-30 and 5W-30 oil. I belived my 88 XJ owner's manual says 0F and above use 10W-30 and 60F and below use 5W-30.

My recommendation is to use a 10W oil, the 30, 40 or 50i is up to you. If you don't get below 0F then the 10W oils will serve you will. The problem with 5W oils is bearing wear on start up sinc ethe film is less thick, the 5W in reality is more for Canada than the the USA.

Also in the Mid 80s I worked at the Missouri Highway dept and the mechanic beat into my head 2000 mile oil changes. So on that 86 Mustang 5.0 I changed oil every 2000 miles and used 10W40 until the jiffy lube type places started upcharging for the 40 oil then I went to 10w-30... for the stang 10W-30 or 10W-40 were both acceptable for the warranty. My mustang never had an oil related problem, and did not puff smoke. I sold it in 1999 with 154,000 on it.

With hotter climates you want the second number larger, so for starters use 10W40 like eagle says, if you have an oil consumption problem then move up to a 10W50.

Martin

At one time, I used to believe the Hype about motor oil. I was a tried and true Castrol fan..partly because of their marketing scheme.... anyway....

If you look on the bottle you'll see an API service code I believe that the Current code is SJ. As long as that dino oil conforms to the current API code, you'll be fine.

Also, if you change your oil regularly, it shouldn't matter what brand or type you use. I'm not sure if a change to synthetic would be in your best interest considering that you don't know the vehicle's history. (oil changes, what was replaced, etc)

John

John-Boy said:

At one time, I used to believe the Hype about motor oil. I was a tried and true Castrol fan..partly because of their marketing scheme.... anyway....

If you look on the bottle you'll see an API service code I believe that the Current code is SJ. As long as that dino oil conforms to the current API code, you'll be fine.

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I disagree with you. Even Wal-Mart's house brand oil supposedly meets the API specs, but I don't think it's as good as Castrol.

Look at the oil. A good oil should be a clear honey color. Since the merger, both Quaker State and Pennzoil are now a slightly dirty brown right out of the bottle. That's why I stopped using Pennzoil.

Actually, of the dino oils my favorite, the one I ran when I was racing, is Amalie, but it's not carried by most of the parts chains and the distributor I used to buy from is out of business. As far as I know it's still very good oil, but I don't know where to get it. Hence my recommendation for Castrol or Valvoline.

I just looked at the American Petrolium site and the current spec for gasoline engine oil is SL, and for diesel engines is CI-4.

There is merit in picking an oil that rated for gasoline and diesel engines. You get the diesel addatives which gives you a little more protection. My Mobil 1 has a API serive of SL/CF

Here a link ot the API and a handy table about engine oil, you will need adobe to read it: http://api-ec.api.org/about/index.c...=display_body&er=1&bitmask=001002003002000000

At MINIMUM you should buy oil that meets the API standards and has the "certified for gasoline engines" seal on the bottle. For some reason choosing a brand of oil is a very personal item, I am not telling anyone what brand to use but just going to say you get what you pay for. Remember the oil you put in the engine and how often you change it is the only thing we can do as an owner to extend engine life.

I switched to Pennzoil full synth at 60K miles and then to M1 10w30 at 80K with the M1 301 filter. At 96K I don't burn any oil and the rear main weeps only a little bit of oil. My engine takes a little longer to warm up with the M1 and overall runs a bit cooler versus the Pennzoil synth. At oil changes the oil M1 comes out with a visable red tint, not completely black. I'm sure its still doing its thing and cleaning out any crud.

Oil is a very personal thing, but I will say I am very satisfied with what synthetic lubricants provide over their conventional counter parts.

--Matt

5 miles per day is not good, the problem is condensation in the crankcase. When you fire it up first thing in the morning as the engine starts to warm up it condenses that cool air that is inside the engine and inside the exhaust system. Provided the engine reaches and maintains operating temp for about 30 min or so this condensation gets cooked off. You can check this by driving to work, shutting it down and pulling the dipstick, expirence tells me that the oil is still going to be pretty cold on that dipstick. If you live in a dusty environment it gets even worse, you are 'extreme duty' as defined in the owners manuals and need to change oil more often. I would, for the cost, stay away from synthetics, you would be better off going to a 2000 mile cycle or maybe even 1000mi. If you do alot of off road I'd buy my air filters by the case.
Personally I have never had a 5 mi commute except when I was stationed at Perl Harbor Hi and lived off base down in back of the international market place in Honolulu. That commute was rough on the bug I had but with the navy exchange selling QS, Valvoline and Penzoil for .35-.55 a quart, oil changes were cheap, more or less, course it's all relative when you are only making $247 every two weeks and your share of the rent is $100 out of each paycheck

Havoline 10w-30 cheap and works, no tickin lots of oil pressure

motorcraft

one question about this discussion...what about motorcraft filters? i have been using fram but i have this feeling like there not good filters. i ask about motorcraft because they sell them at the wally world here and my wife practically lives there
and i was just woundering about them since im usally browsing there automotive sec. waiting for my wife.

http://www.minimopar.net/oilfilterstudy.html

Fram filters are about the worst possible choice. Don't remember what the study had to say about Motorcraft, but Purolators are good and they've carried my '88 for 236,000+ miles (and still running strong) so I'm not about to jump ship.

Thanks All,
That short commute does have me worried because it puts me into that "extreme duty" region. I never thought that short commute would be a problem! The 2000 mile change cycle w/dino oil sounds like the ticket. Or maybe a bigger house further from work, hmm...

RichP said:

When my 82 S-10 with it's 2.8L started leaking oil around 650,000mi ...

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Rich... 650 000 milies?