How to tell if engine needs thicker oil as it ages (miles)?

[TallPaul]

Below is a Nov 14, 03, quote from the Question of the Day "HTHS" thread. I find it interesting that increase in oil consumption as an engine may be related to increased clearances from wear. This might be a good way to judge when to move up to a thicker viscosity (or perhaps an oil with lower NOACK loss?). But what other ways are there to judge the need for a thicker oil? Oil pressure reading lower on an aged engine? And how do we avoid going too thick (i.e. I think most of us would agree that our daily drivers would likely never need a 20w50 as by that point it is time for a rebuild perhaps)?

quote:

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Originally posted by MolaKule:
I think one also has to take into account that as the engine ages the clearances open up and the need for slightly higher viscosities is warranted.

I have seen this in my '92 Burb V8 engine as it crossed the 175,000 mile mark, the 5W30 oil loss was going up (about 16 oz between changes) and the 10W30's were put in place. However, at 280,000 miles, the engine does not use any oil with the 10W30 and compression is excellent with no leak down.

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[dropitby]

So its oil loss between changes and or oil pressure drop . Would this pressure drop be at idle when hot or higer RPM without a sustained high pressure.

 

[c_rossman]

I would also go by oil pressure. You want to run the thinnest oil that substains decent oil pressure.

 

[jorton]

Send me instructions for converting my gage to show actual oil pressure.

[email protected]

 

[jsharp]

I would think that high lead readings in a used oil analysis might also indicate a need for a thicker oil regardless of age.

The most likely place to see low oil pressure would be hot idle...

 

[Ugly3]

Most cars on the street do not have an oil pressure gauge - they have an idiot light.

Oil consuption on a high mileage engine would probably be the first indication that you might want to try the next higher weight oil.

If you had an oil pressure gauge then low pressure at hot idle would probably be the first indication.

 

[Spector]

Currently trying this by going from a 10W30 to 15W40 with no changes in anything so far. In fact, Blackstone implied that a heavier weight may in fact cause more bearing wear. If the wear rates remain the same and the consumption then it will be back to the 10W30.

 

[Dr. T]

Viscosity selection should be based on temperature. Never exceed the 'viscosity chart' recommendations for your prevalent ambient temperature range regardless of engine wear.

 

[TC]

One question that popped in my mind was that, barring any oil pressure or consumption issues should these arise, is this something that needs to worried about? Is eventual normal engine wear taken into accout when powerplant engineers specify a given oil weight for a given engine? The obvious speculative answer to me would be yes -- any other viewpoints?

 

[Geoff]

Thicker oil can help restore compression also on older engines.

 

[Robbie Alexander]

quote:

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Originally posted by TallPaul:
And how do we avoid going too thick (i.e. I think most of us would agree that our daily drivers would likely never need a 20w50 as by that point it is time for a rebuild perhaps)?

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[/QB][/QUOTE]
You simply go with the next size up.
5w30, to 10w30 not 20-50, which may be after say
a 15w40.

 

[jthorner]

Increased oil consumption would be my trigger point to try a slightly thicker oil. Oil pressure is nice to monitor, but very few vehicles have an accurate oil pressure gauge, or any at all.

John

 

[cryptokid]

you can buy an oil pressure gauge at walmart complete with all the fittings and hose. you can remove the oil pressure idiot light sending unit and temporarely run with the gauge to see youre oil pressure. then remove the gauge and reinstall the sending unit.

this way you can use it to test multipule cars.

the gauge kit costs $10 dollars.