using higher viscosity oil

My manual calls for 5W-30 or 10W-30. It doesn't get freezing here so I've been using 10W-30 synthetic. 303k miles.

I have an unidentified small oil leak, a few drops a day on the garage floor, not enough to affect oil level. I checked hoses, valve covers, oil cooler, oil filter. I think it will be something more expensive that I would rather leave alone.

Would switching from 10W-30 synthetic to 10W-40 synthetic make sense to possibly stop this leak? I've heard thicker oil causes bad fuel economy, sludge, and it won't flow into small areas as easily, but then people also say it's a good idea in high mileage engines.

 

It can be a leaking seal. You can try a can of seal rejuvenater. Seals get hard and leak when they get old. Its a temporary fix. Eventually you will have to replace the seals.

 

If you want to thicken your oil a little, might try the synthetic lucas.....

 

It's a good idea for higher-mileage engines when the issue is internal wear, that is the tolerances in the bottom end, wrist-pins, etc, have worn, and cause a resulting loss of oil pressure. Increasing the viscosity will do nothing to stop this leak, and could, in fact exacerbate it by increasing the oil pressure in the engine.

 

If you want to get little more life out of your seals, the concentrate they use in high milage fluids...
ATP AT 205... HOWEVER it is indeed to get a little more life.....should only be last resort....

 

Your safest bet is to go get UV dye kit off amozon and the find the leak yourself...
all kinds of vids how to do this....

You can find if its an idle leak, or high press highway one....

 

Why not just track the leak down and fix it properly. Seems silly to roll the dice on an otherwise sound engine.

 

Edit is the drain plug and oil filter fully tightened?

I'd switch to a 30 weight high mileage conventional, they have seal conditioners that can help

 

Again if you use high milage oils and dont have seal leaks, those conditioners cause butyl parts to swell unnecessarily, causing them to wear.....

There are some amazing products out there for aging engines, even high zinc's for restoring compression, but BUT, they all have side effects.

If you've got alot of carbon build up in the engine, thicker oil might be wrong direction...
So got to diagnose carefully, get oppions....
Lucas flush comes to mind, it could save old beater, or become your worst nightmare....

 

Using heavier oil seems to me that you will put more strain on the oil pump.

 

Yeah, using a flush on a sludged engine can end up freeing up gunk that blocks the oil pickup screen or oil galleys in the head. Ask me how I know

 

I've heard that the stop leak products like ATP are more like emergency fixes that are likely to cause problems?

If a higher viscosity could make it worse, would switching to 5W-30 synthetic be a good idea for this or any other reason? I was going by the manual diagram. I occasionally am in hot weather and freezing weather, so I just chose 10W-30 because I'm in hot more often.

As far as locating the leak, I've gone through many cans of degreaser, repeated over months, to get rid of the old gunk before trying to identify new oil. The problem now is the front area of the engine is gunked up, and I'd need to remove the drive belts and that plastic cover behind them to start spraying. I'm not doing any of that. I don't even know if it's coming from there. I see the shine of oil on the gunk, but maybe that's been sitting there for years. The oil is dripping further back, off the bell housing.

 

hopefully thats good news.....a rear seal could last long even dripping a little.
Other guess would be valve cover.....and again no big deal.....tackle it when your in there doing something else...

 

Are you certain it’s engine oil, not gear oil (smelly) or psf (red)?

 

Mostly sure. It's the yellowish color of my engine oil. RWD so no gear oil up front.

 

Ok, good to know…sorry I missed the rwd detail. FWIW, I run Mobil 1 0w-40, since it shears down to a good 30 weight fairly quickly. Point being, fiddling around with the oil itself probably won’t make a big difference. High detergent oils can clean up a sludgy engine, and high mileage oils can help with consumption, but for a visible leak, it’s best to either fix it or live with it.