Mixing syn 5w40 and dino 15w40

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My van's rear main leaks, crank is worn down and I replaced the seal. Running dino 15w40 slows it down a ton but I can't stand how thick it is when its cold. Love running the 5w40 but I'll never have to worry about the underneath rusting,
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I have Rotella synthetic 5w40 and dino 15w40 so I was thinking mixing it 50/50 to help with the rear main leak and still have some synthetic for cold starts. Thoughts?
 
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Many times I have recommended LM Motor Oil Saver and its reduced the leak. High mileage oils like pennzoil or valvoline maxlife might help. Tried White Shepard Leak Seal, and it fixed rear manifold gasket on 94 grandprix, but didnt do anything to the old cork gasket on tranny. Costs some coin but I think they still have a satisfaction guarantee. Good luck.
 
I'd probably go with a HM 10W-40. Probably no more expensive than your dino 15W-40, thinner when cold, may help slow the leak, and most HMs are syn blend.
 
Originally Posted By: KD0AXS
I'd probably go with a HM 10W-40. Probably no more expensive than your dino 15W-40, thinner when cold, may help slow the leak, and most HMs are syn blend.


Never mind this, guess I'm still half asleep this morning. Didn't realize we're talking about a diesel here.
 
MaxLife 10w40 is CF rated, so it's good for IDI diesels built up to 1994. I say give it a try. All MaxLife oils are synthetic blends, and have a good reputation for slowing or stopping leaks. Plus, you'll definitely have a 10w40 oil instead of a maybe 10w40 oil.
 
All I ever ran in my '83 6.2L stake bed was 15W40 or SAE30 Delo. Retired the truck with the motor running well at 478K miles. That included below freezing starts (many times not plugged in).
 
I agree with Papa Bear. Looking at the weather forecast for your area, I would stay with 15W-40 rather than blending.
 
I'm running Bars Leak Rear Main Seal Repair in the 7.3 IDI seems to have slowed the rear main leak a little-is your CDR valve working? Wonder if they make a Speedi-Sleeve for your 6.2-that's what I'll eventually have to put on my 7.3 to stop it.
 
LOL, thanks guys. Your right, it doesn't get that cold but we do get freezing temps and I just don't like the sound, hehee.

Its a bugger to start on my fuels so it needs all the help it can get, I have new battery's and a starter and plug it in, plus I basically start it and hit the highway.

I could get a speedi sleeve but don't feel like pulling the engine, too much work plus a new engine is going in soon, aprox 6 months, found a GEP engine which has the one piece rear main seal.
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I am sqeamish running a 10w30 but if you guys feel its ok I'll try that.
 
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If the engine is coming out in 6 months, then it doesn't matter much. Just dump any decent 10w40 in it. How many miles can you run before adding a quart?
 
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Originally Posted By: sixtwoturbo
I am sqeamish running a 10w30 but if you guys feel its ok I'll try that.

My dad had a 6.2 of the same vintage as yours. He switched to 10w-30 in the fall every year. It lasted forever and a day; I wish the thing was still around.
 
Thanks guys. I have to add a quart about every 700-1000 km's, depending on how hard I drive.

I can't have it blow up yet, still building the other engine.
 
So you get a complete oil change in about 6000 km's. Stop changing oil and just change the filter every 10,000 km's. Use any decent SM/CF oil you can find. With such frequent oil topoffs, the oil will not get into a soot-loading problem.
 
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