20w 50 for an XJ?

It was suggested to me that I try a thicker oil to quiet my engine noise. I'm using 10w 40 now, and I'm curious to try 20w 50 would it hurt anything?
I have an 88 XJ 4.0 4spd at.
Any thoughts?
Thanks, Sam

If it's old and loose then 20w50 would be fine.

Define old and loose.
163k miles?

I run 20W50 but I'm in a hot climate and over 350,000 miles. Been running the 20W50 since around 200,000, It's an '88 XJ 4.0 The Renix's seem to really hold together...

Dunno - I run 10W-40 in my 88 (you've seen it, I think) with almost 250K on it. What sort of noise are you hearing?

5-90

So am I understanding that 20w 50 is a good oil for older engines?

I run Castrol GTX 20-50 in both XJ's.
The 99 has had it all its life. 140,000 miles and still going strong.
ONLY problem I have EVER had with it is the waterpump.

BTW...
i run Fram filters too.
(as they say... "flame suit on")

sorry about the double post - computer and I are fighting again.

I am running 15-40 Rotella and my MJ STILL rattles, but at least it has pressure when it warms up now ( around 20 lbs at warm idle now ). If your motor still rattles after the thicker oil, you may consider changing out the lifters, as they have been known to wear out on the cam side and then constantly rattle. I am not worried about my rattle, since the motor still pulls strong and there is NO noise in the bottom end ( rod tap/knock ). Oh, yeah the motor has around 187,000 miles on it.

The PROPER Viscousity Oil is the best for any engine. Whats proper, most likely whats recommended for your motor by the manufacturer.

An older motor that has greater clearance between bearing sufaces and suffering from low oil pressure, may regain some oil pressure by using a higher viscousity oil. So go off the oil pressure to decide if you should switch to higher viscousity.

As far as qieting the motor, it may work, it could make it worse. Whats making the motor noisey? If its from gummed lifters and valvetrain, higher viscousity may make more noise.

86 2.8l, 87 4.0l, 91 4.0l HO, 93 4.0l HO all run with 20W50 and Mobil 1 filters.
They have over 140.000 with no problems.
Just remember heavy oil is not a fix for low oil psi.

73's KG4BET

SAE 20W-50:

contains seal conditioners that help reduce leakage. It exceeds API SM and is recommended wherever API SM, SL, SJ, SH, SG and previous API S categories are recommended. Use GTX HIGH MILEAGE 20W-50 when the ambient temperature is above 20 degrees F.

Oil psi is fine maybe a little high (50-55) at 65mph. The noises Im getting are noisey lifters, I think.

If your lifters are noisy, thicker oil might help, but a good flush, perhaps just a very short oil change interval with thin high detergent oil, might help more. If they're sticky or grungy, the flush will help. If they're worn out it won't. If the noise is from piston slap, it won't make any difference.

Others may differ on this, but I prefer thin oil as long as pressure is good. The theory here is that as long as the oil is cushioning the bearings, it's doing its job, and the thinner it is, the faster it flows with less effort, and the more heat it carries away. If you have enough pressure, then you have enough pressure. The engine really doesn't benefit from more than enough.

Concur.

If it's lifters, a definite flush is in order - even it's just running a quart of Marvel Mystery Oil with your next change (sub one quart MMO for one quart of oil.) Don't ask me how it works - but it does tend to break up varnish and crud, and make things a little smoother and quieter. If you run MMO, make sure you drain your oil HOT so it carries away as much as possible.

Failing that, running a "heavier multi-weight" isn't a cure-all - but you can mix weights. I've done that with a few other engines before - sub in a quart or so of 40W or 50W for a like amount of 10W-30, and that will give you a thicker base.

I'd be more inclined to try to clean things first. Use either a quart of MMO and run normally, or maybe a quart of Diesel and idle for 15-30 minutes (DO NOT DRIVE!) Either way, drain the oil HOT - more will be dissolved in the oil while it's hot, and more will be carried out when you drain the oil. Hell, even running olive oil (yes, I've done this - but not to clean out the engine...) will clean things out.

I will usually go so far as to run a few errands on "oil change day" so I can drain it hot, which helps keep things clean.

5-90

langer1 said:

SAE 20W-50:

contains seal conditioners that help reduce leakage. ....Use GTX HIGH MILEAGE 20W-50....

Click to expand...

I don't "THINK" all SAE 20W-50 contains seal conditioners, I "THINK" that is a special additive that manufacturers add for a derivative of their oil that they label "High Mileage".

Often all the conditioners do is contain some sort of chemical that causes the seal to swell. It could help, it could hurt. If some of the seals around rotating shafts are in good shape, what happens if they swell? They could get torn up because they press too hard against the spinning shaft.

There was a post not long ago from a guy that switched to "High Mileage" oil and immediately developed a rear main seal leak, I wonder if my above scenario is what happened.

Matthew Currie said:

Others may differ on this, but I prefer thin oil as long as pressure is good. The theory here is that as long as the oil is cushioning the bearings, it's doing its job, and the thinner it is, the faster it flows with less effort, and the more heat it carries away. If you have enough pressure, then you have enough pressure. The engine really doesn't benefit from more than enough.

Click to expand...

I agree,

BUT I wouldn't use an oil thinner than recommended for the conditions. The additional logic behind that is, viscousity "usually" is related to shear or film strength of the oil. Thats the resistance of the oil of being force out from inbetween two metal parts and allowing metal to metal contact.

So even if the thinner oil gives you adequate oil pressure, it may not give you enough shear resistance to prevent metal to metal contact. Things like some of the valvetrain don't rely on oil being pumped into a bearing, but rather oil being dripped or sprayed in between rocker tips and valve stems. So even if there is enough oil pressure, if the film/shear strength isn't high enough then you may get metal to metal contact.

As well, I think the manufacturers probably have a big debate amoungst their staff about recommended oil viscousity, with the pressure leading to recommended the thinnest oil that is safest to use, so that they can get higher mileage and energy savings on the vehicle. I'm sure there are engineers that scream that the viscousity should be higher, that under some conditions that low of a viscousity could lead to metal to metal contact and extra wear.

THUS, I wouldn't use less than recommended viscousity, ACCORDING TO CONDITIONS. Look in you drivers manual, there are temperature ranges that go along with the viscousity recommendations, pay attention to those, for some of use a different viscousity than all the others use may be in order.

I said film/shear strength is usually related to viscousity, thats a general trend type deal. All things being equal, higher viscousity oil inditical to the lower viscousity in all things except viscousity, the higher one will have more film/shear strength. Qaulity, composition, additive packages, conventional/synthetic all affect that as well.

Good Quality 5W-30 Synthetic may have more film/shear strength than poor quality 20W-50 conventional oil.

So what, then, would be considered "High Mileage?"

I've got nearly 250Kmiles (probably turn it over next week,) and I still use regular Castrol 10W-40. No problems, no leaks, no noises. Been using that since I got the thing - it's what I run in everything!

5-90

Matthew Currie said:

Others may differ on this, but I prefer thin oil as long as pressure is good. The theory here is that as long as the oil is cushioning the bearings, it's doing its job, and the thinner it is, the faster it flows with less effort, and the more heat it carries away. If you have enough pressure, then you have enough pressure. The engine really doesn't benefit from more than enough.

Click to expand...

Agree. As long as the oil pressure is more than 13psi at idle and more than 37psi at speed, you don't need a thicker oil. The 4.0 engine doesn't like an oil pressure over 60psi for two reasons. Firstly, the higher oil pressure causes seals and gaskets to leak (especially the rear main). Secondly, a high oil pressure puts more load on the oil pump and since that's driven by the distributor shaft, distributor drive gear wear is accelerated.

I'd be more inclined to try to clean things first. Use either a quart of MMO and run normally, or maybe a quart of Diesel and idle for 15-30 minutes (DO NOT DRIVE!)

Click to expand...

Sounds like a good idea.

kg4bet said:

....Just remember heavy oil is not a fix for low oil psi.

Click to expand...

True, BUT;

Low oil pressure can increase the chances of metal to metal contact on bearing surfaces that rely on pressurized oil being pumped into them. A thicker oil can prevent help prevent that when an engine is suffering from low oil pressure.

You probably agree, I don't mean to correct you, but just add to the point.

We probably both agree, if you have low oil pressure the real cure is an engine rebuild, a thicker oil will only help treat the symptoms before you do the rebuild.