winter oil ?

I have rotella 15w40 with a quart of Lucas currently in my 4.0l.

as the weather is getting into the 30s I noticed the last couple of days when I started the jeep I would get a screeching sound 2-3 seconds after the engine started. I need to have someone start the engine while I open the hood to see if I can tell where it is coming from. I guessing its maybe the belt... But could the oil be to thick and something in the engine is rubbing metal on metal do the delay in getting the oil running. After the first start in the morning I do not heard the noise again for the rest of the day.. Should I drop to a 5w40 for the winter? With / without lucas?

I recently checked on recommended oil weights for my '01 XJ.
10W-30 is specified down to 0F.
5W-30 for -15F up to 35 (I think it said)

I'm not saying that's the noise but.... why would you use the wrong weight oil?

^x2. I know people run Rotella because of the zinc but if you want, you could put some of that oil (15w40) outside at night and see whats it like in the morning. I would assume its like honey. Rotella is meant for diesels and those usually either run continuously and have block or oil heaters

Yeah, I don't think the ZDP in Rotella is going to help you much if it's like honey when you start. You would probably be better off just using the Rotella for the additives in fair weather, and switching to 10w-30 or even 5w-30 in cold weather. Oil flow is more important than any additive, IMO. Lucas is going to make it even thicker...

With that said, I would bet your screeching is your accessory belt. The alternator has a much larger load on it when starting in the winter, because the battery is using so much power to turn over the motor. Mine screeches just slightly on cold starts. I would suggest you put about a half turn more on the belt tensioner. If you have reduced noise, you have determined that it is indeed the belt.

Primarily OVER 60 degrees farenheit, I use 10-30
Primarily UNDER 60 degrees farenheit, I use 5-30

That recommendation is per my owners manual and I have no reason to second guess that as it seems reasonable.

The screeching is not your oil. As you mentioned, have somebody start the engine while you listen. I'm betting on a belt. Inspect it for glazing and wear and if it's old, just replace it. I like the Goodyear Gatorback belt. Be aware that the belt on the 4.0 needs to be awfully darn tight on the 4.0 to stay quiet....

thanks all for your feedback.

I was running 15w40 to increase my oil pressure but with winter here I may drop back down to 10w30.

I doubt the screech is from your oil but 15w-40 is a bit thick for winter use unless you are trying to stretch the life of a thorougly worn out engine. It's a nice feeling to have higher oil pressure than you absolutely need, but I don't think your engine really cares as long as it's enough. You'll get a little quicker lubrication and fewer cranking amps on cold starts with something thinner.

15W30 by itself is plenty think. Lucas on it's own has the consistency of honey, so I would say the combination of both is a bit too much. I had the same combination at one point last fall and on the first cold morning it made all kinds of not-so-nice noises. Wound up going back to what I had been doing before, 10W30 in the summer months, 5W-30 in the winter months.

TheJerm said:

^x2. I know people run Rotella because of the zinc but if you want, you could put some of that oil (15w40) outside at night and see whats it like in the morning. I would assume its like honey. Rotella is meant for diesels and those usually either run continuously and have block or oil heaters

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Really it depends on the series of Rotella- t5, t6, full synthetic or not.
"Rotella is meant for diesels" is really a misleading statement- the back of the bottle even says recommended for motorcycles, cars, trucks, ect, not just or "only" diesels.

Avoid using the Lucas. They make great gear oil and nice fuel system cleaners, but the oil stabilizer is something that will never be run in my Jeep or any engine I own. If you research the chemical composition of the oil stabilizer, it is mostly oil thickeners. Fine for something that has an engine knock that you are trying to squeeze a few more miles out of, but not an engine you plan on keeping.

The ZDDP needs of the 4.0L are also a myth. The valve springs in a stock 4.0L are fairly weak and won't cause any excessive wear on the cam when using a passenger car motor oil. A stroker motor with an aggressive cam may do better with a heavy duty engine oil such as Rotella, but a stock motor will be fine with any 5w30 or 10w30 changed at the proper intervals with a good filter. ZDDP levels have been decreased in motor oils, but other anti-wear additives have been added in place of it. If you have a high mileage motor and it makes you feel better to run a 40 weight, then try Rotella 5w40 synthetic. You are doing more damage to the engine running thick oil in cold weather than you possibly could running a thin oil in the summer. I'd say run a good 5w30 like Pennzoil Yellow Bottle 5w30 or Valvoline Maxlife 5w30 and you should be good. :wave1:

I've run 15w-40 in gas engines for years with no problems at all. The high detergency and other diesel-friendly stuff might be more than you need, but I don't think it hurts anything either. I just don't think it's such a good idea to run that high a viscosity in winter, even if your engine is old and loose. You'll get quicker circulation, and probably a little better cold weather mileage, if you stick to what's recommended.

I'm with others here, not to bother with "mouse milk" unless you're trying to finagle a few last miles out of a dying engine. Good oil is good enough.

so I went to a heavier oil to help with my low psi. I had it checked with a mechanical gauge and I'm getting 10 psi at warm idle and when we rev the engine it doesn't go pass 35 psi. Mechanic says it's within low end of tolerance and to just drive and not abuse her.

For our 4.0L IIRC 10psi per 1k rpm is min., 35 isnt bad for top end.
I run Amsoil AMO which is 10w-40 with added zddp doesnt usually get below freezing here, but depending on how cold it gets you will want to run lower xxW weight for cold starts. When I was living in WA state I ran 10w-40 in my vehicles most of the year and 5w-40 in winter.

Here's an interesting post regarding oil pressure. His problem was solved. Could we have been overlooking this possibility for a while?

http://www.jeepforum.com/forum/f19/4-0-low-oil-pressure-idle-fixed-1304679/

Reading on Bob is the Oil Guy, people say that the 4.0s show good wear numbers on a 40weight oil.

The issue is running a 15w dino oil on cold start - TOO thick.

Use Rotella 5w-40 ... it'll be thin enough on startup (being a 5w synthetic) but will warm up to be a 40 weight.

I'm gonna try a lighter weight oil.

But, I think the real issue with 4.0s losing oil pressure and having worn internals is the use of crappy oil filters with poor anti-drainback valves. The use of such filters causes dry starts that are much more severe than a slower flowing oil.

cruiser54 said:

I'm gonna try a lighter weight oil.

But, I think the real issue with 4.0s losing oil pressure and having worn internals is the use of crappy oil filters with poor anti-drainback valves. The use of such filters causes dry starts that are much more severe than a slower flowing oil.

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Flow, not pressure determines lubrication.

If I could have found a CHEAP 0w-30 I would have run that in mine for winter.

Modern engines (with the exception of the minivan engine in the JoKes) last a looooooong time on light oil.

cruiser54 said:

Here's an interesting post regarding oil pressure. His problem was solved. Could we have been overlooking this possibility for a while?

http://www.jeepforum.com/forum/f19/4-0-low-oil-pressure-idle-fixed-1304679/

Click to expand...

That's an interesting thought there. Certainly is easy to do. I wonder if that's why my 95 always had great oil pressure. I ran it for a long time with bad O-rings, until it was gushing out about a quart a day. Perhaps that flushed it out. It was still running a good 45 pounds hot when I sidelined it at 263K. My 99, which is due to hit 263K tomorrow, is only in the 40 range hot. Maybe I'll pump some oil out of the gauge hole and see what happens. I'll post back if I do.

Miller88 said:

Flow, not pressure determines lubrication.

If I could have found a CHEAP 0w-30 I would have run that in mine for winter.

Modern engines (with the exception of the minivan engine in the JoKes) last a looooooong time on light oil.

Click to expand...

I agree that flow is more important than pressure in regards to lubrication. My point is that when we use el-cheapo oil filters on our Jeeps with their upside down and sideways oil filters, there is NO FLOW for a few seconds. This is worse than slower flowing oil being there instead.

agreed oil filer quality is very important - they need a good anti-drainback valve. I run 5w-30 blend oil year round - always starts right up and has great oil pressure - at 250k miles.