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I have an oil leak on the lower driver side of the engine. The front diff area and the oil pan are all soaked as well as the frame behind that. Mid and upper engine is totally dry. I know most might say it is just a front diff problem but my engine oil is going down regularly. Lost about half quart in the past two weeks and another half in the two weeks previous. I just can't find where it's actually leaking from despite being under the truck every day. Where is the most likely leak site given what I've posted?

Thanks
On amazon look up ACDelco 8792S advantage crankshaft oil seal
It is priced at 7 dollars its a small thing that goes behind the crankshaft pulley this can be one of the issues if it is not coming from the crankshaft then look at timing gaskets as this would be next i found them priced at 35 these are brand new not used parts i priced im in America so the prices will be up a little more for you probably amazon will allow you to input make a model of your truck to ensure it fits so you don't get the wrong part they have saved me hundreds on repairs the labor is still gonna be close to the 400 dollars though
Is this the seal?...

Is this the seal?...

Yes that looks like its it I would suggest making sure where the leak is exactly coming from 1st before ordering it to make sure that's what you need it is possible that the timing cover seal busted on that side so only the driver side gets sprayed if you look down by the crankshaft pulley with a flash light see if it has oil on the back side of so that seal is more than likely the issue if not then look at the oil pan gasket and the timing cover gasket those are the only thing the would leak oil on that side of the motor if its the oil pan it will have oil mainly where the leak would be and same for the the timing cover
 

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2007 Trailblazer LT
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Discussion Starter #23
Yes that looks like its it I would suggest making sure where the leak is exactly coming from 1st before ordering it to make sure that's what you need it is possible that the timing cover seal busted on that side so only the driver side gets sprayed if you look down by the crankshaft pulley with a flash light see if it has oil on the back side of so that seal is more than likely the issue if not then look at the oil pan gasket and the timing cover gasket those are the only thing the would leak oil on that side of the motor if its the oil pan it will have oil mainly where the leak would be and same for the the timing cover
When I look down at the engine from above at the pullies and the belt, you cannot see any evidence of oil whatsoever. You have to get under the truck to see the mess of the leak. Can you elaborate a bit more on the timing cover gasket and what's involved in that repair? ... unless I'm confusing that with something already covered...
 

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When I look down at the engine from above at the pullies and the belt, you cannot see any evidence of oil whatsoever. You have to get under the truck to see the mess of the leak. Can you elaborate a bit more on the timing cover gasket and what's involved in that repair? ... unless I'm confusing that with something already covered...
For the timing cover it sits in front of the motor behind all of the pulleys all of the pulleys the belt water pump and fan clutch have to come out to get to it its uses oil to lubercate the gears for the camshaft and crankshaft to work properly it still gonna be probably about 400 cause the front of the motor has to come apart not to mention its a pain to get to all of the bolts holding it on if the gasket busted on it then there should be one section that has more oil on it then anything else if it is the oil pan then the only challenge is getting it out from under the truck but once its out it's a cake walk till you have to put it back in again there will be one spot with more oil on it than any other
 

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2007 Trailblazer LT
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Discussion Starter #25
Thank you very much for the explanation. I hope the problem is the whatever is easiest and cheapest!
 

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Thank you very much for the explanation. I hope the problem is the whatever is easiest and cheapest!
I hope all this info helps you out i know repairs can be quite annoying and expensive i do most of the work on my truck so I've learned allot about it
 

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2007 Trailblazer LT
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Discussion Starter #27
Got this checked and it's a very small rear main seal leak. The mechanic says the amount of oil leaking is very slight and would not recommend tearing the truck apart for it. Frankly I cannot afford that expensive anyway. So, while I know some don't approve of oil additives, if you were to use or have used an oil sealing product, what was your experience and what do you recommend? Lucas? Bar's Rear Seal Fix? Blue Devil? Bar's seems the most convincing but I tend to trust the Lucas brand name more than all others...

Also, should I begin using high mileage oil too? I hear it is better for worn seals etc.?
 

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2004 chevy trailblazer_lt
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Change to a high mileage motor oil like Valvoline High Mileage, Havoline High Mileage, Pennzoil High Mileage, etc. There are several on the market including house brands for Walmart (Super-Tech) and Canadian Tire. I would not add any of the additives you mentioned, and from what I have read on the Bob Is The Oil Guy forum, Lucas products, especially additives, are not viewed very favorably.

FYI, the high mileage motor oils are formulated with more of the seal conditioners (contained in all motor oils) to help them remain pliable and reduce small leaks like what you describe. It might take 2 or 3 oil changes to see the full results/benefits of using a high mileage motor oil.
 
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