engine and drivetrain Oil Blend Effect On Old Engine? Opinions Please.

[PaulTWinterton]

My dilemma: what oil to use?

 

Stock tii engine, 98K.  Original condition, adjusted to spec and running well (considering it's age).  No oil usage issues.

 

I've used 10w30 motor oil in the car for 25 years, as recommended on the hood sticker.  After reading various posts on the FAQ  stating the absolute requirement for 15w50 high zinc, I changed to that blend.

 

Since I did that I have noticed 3 things:

1.  I have a couple of oil leaks. One under the distributor housing and the other on the timing chain cover.  One drop a day, but not there before.

2.  At idle my engine "knocks".  Not consistently, not loud, but  intermittent soft knocking.  Only at idle. 

3.  I think I have more power.  There seems to be a bit more snap to the engine.

 

10w30 versus 15w50.  Is that what's responsible?  Am I hurting my old engine?

 

Thanks for reading and replying.

(My guess? Time for a rebuild.)

 

 

 

[tzei]

Okay here it goes...

My findings are:

1. 10W30 ruins valve train. Doesn't take heat and cooks all over the place.

2. 10w40 - no such issues. Never looked back.

(Race engines are different story)

So to your 15w50 then. 15w might be okay (summer use)and 50 might be too thin hence minor leaks (on an old engine). Fresh rebuild & 15W50 - why not.

Knocking - new oil washed old debris away?

[M3M3]

Okay here it goes...My findings are:1. 10W30 ruins valve train. Doesn't take heat and cooks all over the place.2. 10w40 - no such issues. Never looked back.(Race engines are different story)So to your 15w50 then. 15w might be okay (summer use)and 50 might be too thin hence minor leaks (on an old engine). Fresh rebuild & 15W50 - why not.Knocking - new oil washed old debris away?

You have it backwards......lower viscosity number is thinner, not thicker.

[ray_]

2. Are you sure the knock doesn't go away with the clutch in?

 

...I always thought these motors were spec'd for 20-50.

 

Cheers,

[zinz]

I've been waiting for this thread to catch on fire...

 

Couple of things:

 

Marshal beat me to the punch on viscosity #s.... 

 

15W-50 is not hurting your engine, IMO.

 

If you have a few leaks, it's certainly not an indicator to rebuild your engine!  Compression and leakdown tests will give you good indicators of engine health.

 

The leaky distributer flange is a super-easy repair and shouldn't take more than 30-45 minutes, tops.  http://www.bmw2002faq.com/topic/24919-distributor-flange-gasket/

...order the sealing washer with the new gasket, you will want to replace it. Get with Blunt...he'll set you up with the proper parts.

 

You could re-seal the timing chain cover...but unless it's really puking, I wouldn't sweat it....even freshly rebuilt engines can leak some.

 

You've obviously found a ton of other threads about which oil folks are using... high zinc content is highly recommended.  I agree with Ray and run Valvoline 20W-50 in hot, central Texas. 15W-50 in Vancouver sounds just about right, to me.

 

Ed Z

['76mintgrün'02]

One man's knock is another man's rattle... 

Mine 'rattles' at idle.  I had suspected the timing chain, but I guess it could also be the oil pump chain.

 

'knock' sounds serious... so I don't use that word.

 

I know engines develop higher oil pressures when they are cold, due to the oil being thicker.

Could 15w-50 oil raise the oil pressure, compared to 10w-30 and possibly lead to leaks?

 

That distributor housing leak should be an easy one to deal with, by replacing the paper gasket, rubber o-ring and the fancy little rubberized washer.

 

As for "time for a rebuild", what are your compression numbers?

[tzei]

 

You have it backwards......lower viscosity number is thinner, not thicker.

 Yes you're right thanks for correction.

[Conserv]

 

...I always thought these motors were spec'd for 20-50.

 

Cheers,

Yes, but....that's for south of the Mason-Dixon, unless you change your oil for the winters!

Best regards,

Steve

[PaulTWinterton]

2. Are you sure the knock doesn't go away with the clutch in? ...I always thought these motors were spec'd for 20-50.

 

I'll double-check with the clutch in, but I'm pretty sure it's piston/wrist pin/rod bearing looseness sound.  Kind of freaking me out, but the sound goes away with just a bit of throttle.

 

Hood sticker says 10w30.

 

No leakdown test done, but compression is 140-125-135-140 at WOT.

[TobyB]

I bought one of those $8 'mechanic's stethoscopes' for the rattly land cruiser-

that thing is great!

 

See if you can find where the 'noise' is coming from- the valve train is sometimes louder than you'd expect at idle.

If you can narrow it down to one cylinder, that might not be so good.

And check the exhaust manifold gasket- I'm always amazed at all the noises

a small leak there can imitate.

 

And put an oil pressure gauge on it.

 

15-50 is good in these engines, in my experience.  But 10-40's not terrible.  And 10-30's what we used on

Jenn's engine for the first 10 years...

 

too many words!

 

t

[GreenSwede]

An out of the blue guess for the knock is oil pump shaft. Mine does that, on 10w-60 Valvoline Racing oil. A bit more than it did on 20w-50, I think. 15w-50 should work well, though. Maybe a bit on the thin side in a really warm climate. 

 

Checkable with Toby suggestion of a stethoscope, or maybe the cheaper version of a screwdriver pressed to your ear.

[TobyB]

Ok, I used the screwdriver method for, like, 40 years, but the damned land cruiser engine was so long I would have needed 

a $40 screwdriver, so I bought the $8 stethoscope.

 

It works better!  I'm not lying! It has a diaphragm or something in it that does a far better job than Mr S-K.

 

Couldn't believe it.

 

Also can't believe that the land cruiser has a flat cam, but it seems to be what the problem is...

 

t

[M3M3]

Ok, I used the screwdriver method for, like, 40 years, but the damned land cruiser engine was so long I would have needed a $40 screwdriver, so I bought the $8 stethoscope. It works better! I'm not lying! It has a diaphragm or something in it that does a far better job than Mr S-K. Couldn't believe it.

 

second on the mechanics stethoscope.  great tool!  way bettter than a screwdriver.

 

An out of the blue guess for the knock is oil pump shaft. Mine does that, on 10w-60 Valvoline Racing oil. A bit more than it did on 20w-50, I think. 15w-50 should work well, though. Maybe a bit on the thin side in a really warm climate.

 

15-50 is perfect for brutally hot racing conditions.  all i have ever used in multiple race cars.  mid-atlantic heat can put track temps close to 100deg in summer.

[PaulTWinterton]

I'm starting to understand that for my casual, pacific northwest driving, 10w30 was not bad. Further, 15w50, when used in hot racing conditions, thins out and is perfect for THAT situation.

I'm going to switch back and see if the knocking abates. Like I said it was never there before.

[M3M3]

I'm starting to understand that for my casual, pacific northwest driving, 10w30 was not bad. Further, 15w50, when used in hot racing conditions, thins out and is perfect for THAT situation.

I'm going to switch back and see if the knocking abates. Like I said it was never there before.

10w40 would be fine also.

 

the 15-50 is what most bmw's use today for year round everyday use.  in the days of new 2002's, synthectic tech was not available, so wide grades like 15-50 and 10-60 were not possible.