Chevy & GMC Vans

2000 Chevy Astro. Owned since new. Has always 'burned' a bit of oil. Also had the leaking oil cooler lines.
Now noticed a couple times, but not always, a few drops oil on the garage floor and they appear to be coming from the real main seal.
Have always used name brand 5w 30 dino oil.
Recently purchased other vehicles which have turbos and thus am running Mobil 1 10w 30 synthetic on those vehicles and have been planning to switch to Mobil 1 full synthetic for the Atro as soon as last of my 'inventory' of dino oil is used up.
Mobil recommends the following different oils for a high mileage Astro such as mine when I went to there selection site: http://www.mobiloil.com/usa-english/mot ... tion2.aspx

Premium Protection
Mobil Clean High Mileage 5W-30
Mobil Clean High Mileage 5W-30, a conventional motor oil, is designed for vehicles with more than 75,000 miles. It delivers proven protection of critical engine parts from lubricant-related failure for 5,000 miles or six months, whichever comes first. Mobil Clean High Mileage includes seal conditioner to help prevent leaks in high mileage engines.
Mobil Clean 5000 5W-30
Mobil Clean 5000 5W-30 is a conventional motor oil that delivers proven protection of critical engine parts from lubricant-related failure for 5,000 miles or six months, whichever comes first. It is designed to exceed most engine warranty requirements.
Also Consider:

Superior Protection
Mobil Clean 7500 5W-30
Mobil Clean 7500 5W-30 is a synthetic blend motor oil designed to exceed engine warranty requirements. It delivers guaranteed performance and protection for up to 7,500 miles or 6 months, whichever comes first. Mobil Clean 7500 has 18 percent more cleaning agents than Mobil Clean 5000 to keep your engine cleaner longer.
Ultimate Protection
Mobil 1 Extended Performance 5W-30
Mobil 1 Extended Performance 5W-30 fully synthetic motor oil is designed for today's longer service intervals. It provides guaranteed performance and protection for 15,000 miles or one year. Mobil 1 Extended Performance products with the Advanced SuperSyn System contain extra performance additives to help deliver outstanding engine protection.
Mobil 1 High Mileage 5W-30
A fully synthetic motor oil, Mobil 1 High Mileage 5W-30 is designed especially for higher mileage engines where conventional oil has been used. It reduces the sludge and deposits that conventional oils can leave behind.
Mobil 1 5W-30
A fully synthetic motor oil, Mobil 1 5W-30 with SuperSyn Technology, is the approved and the first choice of many premium car manufacturers, including Corvette.

I was hoping to use a fully synthetic oil but one with possibly seal conditioner(s) to possibly extend the life of the front and rear main seals and one possibly with a cleaner. The only one I can see on their list with a seal conditioner appears to be conventional (dino) oil.

My question is to any one who has used Mobil 1 for a high mileage engine with oil leak from rear or front main seals which one did you use and were there noticeable benefits i.e. did it stop the oil leak?

Might not be the RMS, I had the oil cooler adapter gaskets fool me once. Nothing like replacing the RMS and still having a leak. ](*,)

At any rate, I would keep using the required oil. If the leak is bad, fix it. I go through and make sure all the exhaust and trans hardware is able to be loosened and purchase the seal. Then early on a Saturday I rent a trans jack, drop the exhaust and trans, replace the seal, put everything back together and return the jack before they close. The key is the prep work, break everything free first.

Thanks for the reply. What would you consider to be the 'required oil'. The manual says 5w 30 but nothing of course about synthetic versus ??? because synthetic I think was just becoming available back when the van was new...

My recommendation is to stick with the conventional oil that you have been using for all these miles, I mean kms. I don't think it's a good idea to switch to synthetic on a high mileage engine. Just my two cents.

Green was switched to synthetics when I bought it. Van had like 155k then, no problems with it. When synthetics first came out there were mixing problems, new formulas mix fine. Dino or Syn, just make sure it's 5w30.

I agree that a switch to synthetic might not be good - past experience has show me that oil leaks seem to multiply after the switch to synthetic on high mileage engines - it's happened to 3 vehicles that I know of, no leaks with dino oil and then the switch and then oil leaks aplenty - I would personnally use a high mileage with seal conditioners - I did that to mine and my rear main seal drip appears to have gone. touch wood here... anyway just my 2 cents

Sounds like this is the one you would recommend then...?:
Mobil Clean High Mileage 5W-30
Mobil Clean High Mileage 5W-30, a conventional motor oil, is designed for vehicles with more than 75,000 miles. It delivers proven protection of critical engine parts from lubricant-related failure for 5,000 miles or six months, whichever comes first. Mobil Clean High Mileage includes seal conditioner to help prevent leaks in high mileage engines.

i.e. assuming I were to go to Mobil