Another Oil Leak

[KHE]

more or less the root of the problems are always the oil manifold and the rear main seals. 93-2011

I don't think we've ever had a leaking rear main seal problem on this discussion forum. The second generation cartridge type rear main seals are way better than the original lip seal.

[Cadillac Jim]

Going two posts up, to post #23, KHE pointed out that the dreaded case-half leak is nearly always a seepage, and that the oil manifold is in the oil pan gasket, not the case half gasket. A seepage leak can be sealed by retorquing the bolts and use of sealant on the outside of the area. The oil pan gasket that includes sealing an oil manifold can be fixed with the engine in the car.

I agree that I've never heard of a complaint about a rear main leaking.

[barczy01]

Over the years I have had a couple rear main seals leak, both the majority are the manifolds and the oil pan gasket.

[Tony S45]

Hello all:

First post. I'm learning a lot from the info on this forum. Owned a Nothstar de Ville years ago.

I have recently purchased a mint condition 1993 Allante with 63k miles. All fluids were changed regularly during it's long life including the coolant. It's a pre-V4J (very early Northstar) and all systems work and function as they should. No oil leaks. The car is a weekend/ car show driver and I doubt that I'll drive it more than a couple of thousand miles per year.

The questions:

(1) Recommended oil to use for this 21 year old auto? Synthetic? Mobil or ? What viscosity?

(2) How about oil additives? Noted above are comments about GM additive and STP. Your thoughts?

(3) Can anyone explain the pre-V4J designation and what that might mean to me as I travel through time with this Caddy?

Since this thread is primarily about oil leaks, I'll post other generic Caddy questions separately. Thanks in advance for your thoughts.

Tony S45

[Cadillac Jim]

Tony - this question should be in its own Topic; perhaps an Administrator will move it.

What oil? That depends to some degree on where you live, where you park it at night, etc. For a car that isn't driven much and will have oil changes many months apart, I suggest synthetic oil because it doesn't absorb moisture like dino oil and has pretty much an indefinite shelf life in the car. Contrary to what you may hear, the only down side to synthetic oil is that it is more expensive than dino oil. The difference is that as a manufactured product instead of a refined product, it doesn't have the waxes that make dino oil get thick when very cold, and it doesn't have the light hydrocarbons that emulsify with water and form sludge, and provide a lower flash point than synthetic oil of the same grade.

But there are other things as well. If the engine sits for very long periods, the gaskets and seals may take a set and give you oil seepage. This isn't a problem but can be a nuisance. There are those who will recommend additives or oil formulated for high-mileage cars; my remedy would be to take a two-hour trip at highway speeds once a year.

There has been a lot of discussion over the last few years about the reduction on ZDDP in oils and the mileage between oil changes in cars with flat tappets. For a 1993 model, I would suggest that you simply go by what the owner's manual says; if you don't have one, I suggest 6000 miles or one year with synthetic oil, or 3000 miles and six months with dino oil.

GM recommends 10W-30 for Northstars and you can't go wrong with that. Never use an oil with a number other than 30 for the second number.

I don't recommend additives for the engine oil for a Northstar.

I've used 5W-30 Mobil 1 on the recommendation of my dealers; these cars are a 1989 Pontiac Quad 4 HO, a 1997 Cadillac ETC, and a 1999 Pontiac Grand Am GT, all bought new, and my 2011 CTS-V that I got a year ago. But others will disagree.

[KHE]

Hello all:

First post. I'm learning a lot from the info on this forum. Owned a Nothstar de Ville years ago.

I have recently purchased a mint condition 1993 Allante with 63k miles. All fluids were changed regularly during it's long life including the coolant. It's a pre-V4J (very early Northstar) and all systems work and function as they should. No oil leaks. The car is a weekend/ car show driver and I doubt that I'll drive it more than a couple of thousand miles per year.

The questions:

(1) Recommended oil to use for this 21 year old auto? Synthetic? Mobil or ? What viscosity?

(2) How about oil additives? Noted above are comments about GM additive and STP. Your thoughts?

(3) Can anyone explain the pre-V4J designation and what that might mean to me as I travel through time with this Caddy?

Since this thread is primarily about oil leaks, I'll post other generic Caddy questions separately. Thanks in advance for your thoughts.

Tony S45

10W-30 conventional oil. With the reduced ZDP content of the modern oils, you may want to use Rotella 10W-30 which is a diesel oil that has additional antiwear additives. You can also add a couple of ounces of GM EOS (engine oil supplement) it is motor oil with a very high concentration of ZDP. This used to be around $9.00 (either a pint or quart - I can't remember), then GM discontinued it then re-introduced it at a higher price...

[barczy01]

I shop for ZDDP on ebay.

http://www.ebay.com/itm/5-ZDDP-MAXX-ENGINE-OIL-ZDDP-ADDITIVE-ZINC-PHOSPHORUS-/280550757678?pt=Motors_Car_Truck_Parts_Accessories&hash=item415220d52e&vxp=mtr