Worn Engine - 0w-40 or 5w-50 for Max Longevity?

[Gannet167]

I have a 1991 Mazda 2.2 with 320,000 km's. It runs excellent but my UOA's show a consistent high amount of lead and copper. I live in an area where winters get to -30 and summers hit 100.

I switched to synthetic about 50,000 km's ago and for the last year I've been using Rotella 0w-40. It has excellent cold weather flow and the 40 makes it strong at temp. Some people have UOA's on here that show the Rotella is a tough oil and doesn't shear down much. It should be tough, it's designed for large diesels (but has API-SM certification).

A friend of mine uses 5w-50 in his Shelby and I thought, if 40 is good, 50 might be better. The 5w should still flow relatively well in cold weather (although I could always just do an oil change before winter).

The manual calls for 5w-30, but with my worn engine I'm trying to provide a better level of lubrication and fill up the worn bearing journals with a good level of oil pressure. As the engine is a bit worn, the oil pressure in the bearing journals can't be as high as it was designed to be.

Any thoughts? Although I'm probably splitting hairs, I'm hoping to milk as many km's out of this car as possible. Could 5w-50 be too thick and cause problems with oil seals? Is 0w-40 a better choice here?

Thanks

 

[Oldwolf]

Until now I did not know Rotella came in 0W40. We can't get it here in the US.

It is a T5 product: http://www-static.shell.com/static/can-e.../rotella_t5.pdf

Since you did not mention your engine burns oil I would go with the 0W40.

 

[StevieC]

Gannet,

My SUV has over 320K KM's on it and I'm using 5w20 in it with good results on my UOA's. I have used synthetic since it was new though...

I would stick with a 5w30 unless the engine is leaking or burning oil then you could go a little thicker. No need to change if it's still working.

Higher oil pressure doesn't necessarily equate to better flow or lubrication.

The Copper could be gasket material leaching into the oil. I have UOA's that have shown high SI & Copper in my engine since it was new and it was determined to be gasket material leaching and not actual wear going on.

The Lead has me a bit puzzled, but depending on how high it is, it could be normal for a worn engine.

Can you post UOA numbers for your engine?

 

[addyguy]

If your engine runs well, doesn't burn or leak a large amount of oil, you don't really need a super-thick oil.

If you 'like' the Rotella 0W-40, then keep using that - no real need to go to a 50-weight. Truthfully, a high-mileag 5W-30, like Maxlife, would probably work well in this engine.

 

[Boss302fan]

Originally Posted By: addyguy
If your engine runs well, doesn't burn or leak a large amount of oil, you don't really need a super-thick oil.

If you 'like' the Rotella 0W-40, then keep using that - no real need to go to a 50-weight. Truthfully, a high-mileag 5W-30, like Maxlife, would probably work well in this engine.


I agree!

 

[IndyIan]

Are you looking at the castrol syntec 5W50? I used a jug of it in my ATV last winter, it poured pretty thick at -10C when I did the change. Much thicker than the rotella T 0W40 I used last year. The 5W50 must be still be a 5 winter weight and the atv started fine at -20C but this year I'm back to the 0W40 rotella.
I'd stick with what's working for you now, no one really talks about it here but I wonder about oil pump wear with really thick oil running at low temperatures. In the winter the oil might only get to 150F on anything but highway driving, which with a 50W oil must load up the oil pump pretty good IMO.

I don't have an oil temp guage but that's my theory.

 

[Captain_Klink]

at 320,000 km., you Mazda 2.2 is just a baby.
check back at 640,000 km.
keep using 5w30. that is what got your engine to 320,000 and that will get it to 640,000.

 

[Jim Allen]

The 0W40 is likely OK. The 50 grade... dunno. My first reaction is "too thick." Keep in mind "worn" doesn't mean "worn out." I have pulled very high mileage engines apart, gauged the bearing clearances and found them within spec. If you are wondering what you might do to make a more objective choice, here's what you could do.

1) Look up the factory oil pressure specifications. Every factory manual I've seen has them, usually listed at X pressure at X rpm at a certain temp ("fully warmed up" usually).

2) Install an oil pressure gauge that reads in psi (or KPa as you prefer), either a temporary mechanical or install one permanently in the car for your driving enjoyment and entertainment.

3) Observe the oil pressure and compare it to the factory spec in the listed conditions. Ideally, you would do this using the recommended factory grade of oil, but if you do it with the 0W40, it's still a useful snapshot.

4) If the pressures are lower than the recommended range, you have the leeway to go up a grade or two as necessary to bring it within spec. If they are higher, well, you can go down a grade or two as necessary.

5) Make sure you get the engine really hot before testing, ideally the oil temp should be somewhere near the viscosity rating temp of 100C. Also ideally, this is best done in conjunction with an oil temp gauge, but they are more tricky to install than a simple OP gauge.

6) Bear in mind that only at the extreme end of the engiens life does the oil pressure fall out of spec. My prediction- the recommended oil is likely fine... but you never know unless you test. Or tear down, I suppose.

 

[KrisZ]

Reading threads like this I decided I will not do any UOA's unless I have a problem with a head gasket or something. People look at these numbers and just look for problems they don't have. I'll stick with reasonable OCI's and good oil, $20 UOA will not tell me if my engine is worn out or not, no matter the mileage, we have compression readings for that.

 

[Gannet167]

I'm pretty sure my copper and lead are not gasket material, unfortunately. I will post the UOA's when I have a bit of time to find them. These engines are not known to have high copper or lead in the oil and I don't think there are any gaskets on this engine that have copper in them. I'm pretty sure copper and lead mean bottom end bearings. All other numbers are relatively good.

I agree that the 50 is probably a little extreme. I've thought about installing an OP gauge - maybe a good project. The thing is if it is bearing wear (which I believe it is) then those poor con-rods are beating themselves against the crank. The larger tolerances are just making things worse. The 0w-40 should, in theory, have better shear strength and make it more difficult for the con-rod to shear through the layer of oil and actually contact the crank... in theory.

I bought a car at the auction once super cheap. It drove really well until you got it close to redline, when it sounded like machine gun fire. It turned out to have like 100w oil in it. When I tore it down, the con-rods had about 1/16 inch of play in the bearings. They were literally rattling around. The only reason it ran so good was the thick oil. My Mazda is no where near this bad, but along the same line of thinking, I'm trying to help her out.

What does high mileage oil do differently than regular oil of the same grade?

 

[StevieC]

H.M. Oil just has enhanced cleaning abilities and seal conditioners.

In the case of you thinking it's your bottom end I would look for a slightly thicker oil possibly with lots of molly in the formulation (not an additive) and see if that gives you the cushion you need to bring those numbers down.

Steve

 

[Gannet167]

An engineer friend of mine told me that HM oils have several different grades of oil in them that average out to whatever grade is labelled on the bottle. So the thinner oils get into smaller areas while the thicker stuff builds up in larger gaps and helps fill worn areas etc. I found my engine leaked a little when I used this stuff, but I only used it for 2 or 3 oil changes so I don't have a lot of data to compare.

What oils have a high molly content?

 

[fdcg27]

Could it be that what you really need is higher HT/HS, not merely a thicker grade, although they do tend to run in tandem.
M1 0W-40 does have fairly high HT/HS, as does GC.
Both oils must have HT/HS around 3.5, to meet the Euro specs they do.

 

[CATERHAM]

Originally Posted By: Jim Allen
The 0W40 is likely OK. The 50 grade... dunno. My first reaction is "too thick." Keep in mind "worn" doesn't mean "worn out." I have pulled very high mileage engines apart, gauged the bearing clearances and found them within spec. If you are wondering what you might do to make a more objective choice, here's what you could do.

1) Look up the factory oil pressure specifications. Every factory manual I've seen has them, usually listed at X pressure at X rpm at a certain temp ("fully warmed up" usually).

2) Install an oil pressure gauge that reads in psi (or KPa as you prefer), either a temporary mechanical or install one permanently in the car for your driving enjoyment and entertainment.

3) Observe the oil pressure and compare it to the factory spec in the listed conditions. Ideally, you would do this using the recommended factory grade of oil, but if you do it with the 0W40, it's still a useful snapshot.

4) If the pressures are lower than the recommended range, you have the leeway to go up a grade or two as necessary to bring it within spec. If they are higher, well, you can go down a grade or two as necessary.

5) Make sure you get the engine really hot before testing, ideally the oil temp should be somewhere near the viscosity rating temp of 100C. Also ideally, this is best done in conjunction with an oil temp gauge, but they are more tricky to install than a simple OP gauge.

6) Bear in mind that only at the extreme end of the engiens life does the oil pressure fall out of spec. My prediction- the recommended oil is likely fine... but you never know unless you test. Or tear down, I suppose.


+1

 

[Gannet167]

what`s HT/HS?

 

[garlicbreadman]

Originally Posted By: Gannet167
what`s HT/HS?

the strength of the film i believe

higher = stronger

 

[StevieC]

High Temperature, High Shear

Higher is better yes.

 

[Ramblin Fever]

I wouldn't be running a 50wt oil, no way. That's too much on an engine that size and can actually cause more harm then good, IMHO by starving the engine of oil by being too thick to lubricate accordingly.

Lead can also increase if the intake system is not sealed properly??

 

[mechtech2]

Garnet -
HTHS = High Temperature High Shear.
There is a rating for each oil, just like viscosity.
2.6 to 3.8 is a range for common oils.
Guys around here don't like lower HTHS #s, but engines are not throwing rods because of it.
Sure, more data is always valuable, but I think this one is over valued.

 

[Shannow]

Originally Posted By: Gannet167
An engineer friend of mine told me that HM oils have several different grades of oil in them that average out to whatever grade is labelled on the bottle.


Let me know his name so that I can inform HR in case he applies for a job here.