Best oil for old Saab 900?

[CBraxton]

I've been driving Saab 900s for about 25 years now. For all of this time I've been using Castrol GTX 10W30 with very good results, hundreds of thousands of miles with little engine wear.

My current daily driver is a 1986 900S (16-valve, non-turbo) with about 250,000 miles on the clock. Aside from a valve tap (hydraulic lifters) the engine is still in great shape, runs fine. Given the reduced levels of ZDDP in motor oils in recent years, should I be looking at another oil, or an additive, for best engine longevity? I know some older car owners have switched to diesel-rated oils, particularly for Detroit iron, but I'd be interested in hearing what people are using in European cars of this vintage.

In general the engines on these old Saabs are very long-lived. The transmissions, alas, are another story...

 

[bmwtechguy]

HDEO would certainly not hurt anything but your fuel economy since diesel rated oils are usually more viscous. I am very impressed with Schaeffers oil, and have had excellent results with their 5W-30 syn blend and 15W-40 and 5W-40 diesel rated oils in diesel engines as well as gassers. Their additive package is second to none. Another idea, would be to stick with your current choice which has proven itself to you. But consider the product Auto-RX for cleaning your engine safely while you drive, and then keeping it clean with the maintenance dose. Side benefit is that the stuff really prevents wear as it keeps things clean. You can read up on it at their website or do a search here in our oil additives forum. BTW, wlecome to BITOG! Friend's son has the 9000CD and recently started using the Rotella 5W-40 synthetic (diesel-rated HDEO) and his only complaint was that the turbo is slightly more sluggish when engine is cold. He was previously using Supertech synthetic 10W-30.

 

[saaber1]

I would do an auto-rx 2 bottle clean followed by two rinses, all with conventional oil. Then use redline oil or amsoil.

 

[02Pilot]

I used Rotella T Synthetic 5w40 in my Saab 9-5, and I've used both Rotella and Delo 15w40 in my older BMWs (70s-80s vintage). If you don't want to go 40w, I saw some Rotella T (non-syn) 10w30 at Walmart a couple days ago. Or try one of the 10w30 High Mileage oils.

+1 for the Auto-Rx.

 

[CBraxton]

Thanks for the suggestions! I'm a little reluctant to use a synthetic for fear that it will cause leaks in seals that are 1/4 million miles old. I've had that kind of thing happen in the past with Mobil 1 in old engines. (Plus the Saab mill is descended from a British design to begin with, so leaks are part of its heritage.

I've been using Rotella 15W40 in some old domestic iron but wasn't sure if it was a good idea to use it in the Saab, especially in cold weather. I'll have to check for the 10W30 Rotella, hadn't seen that. I've seen the high-mileage oils (Castrol has one as do others), but didn't know exactly what was different about them. Does "high-mileage formulation" equate to more ZDDP or equivalent anti-wear additives? (What's really in them?)

 

[MI_Roger]

Another high mileage Saab owner here. I have 219,000 miles on my 2000 9-5, and have used synthetic oils exclusively since new. Currently using ELF Excellium 5W/40 NF which is a diesel rated oil. But you said you don't want to switch to synthetic.

The vehicle I sold when we got my wife's new ride was a 1995 Astro van with over 130,000 miles. I switched that vehilce to Valvoline's Max-Life 5W/30 at around 100,000 miles and noticed a difference. The Max-Life is advertised to contain special additives to help old seals; and oil useage, although not much to begin with, dropped to zero after changing oils.

So based on my very limited experience, the "high mileage" oils apparently do perform as advertised in older engines.

 

[CBraxton]

Interesting on the high-mileage oils, it is something to consider. Right now despite the high mileage, this car uses very little oil, less than 1/2 quart between 3000 mile changes and most of that is seepage from the look of it.

What should I be looking for in a diesel-rated oil if I go that route? CI-4 or CI4+ rating? What should be avoided? Though from what I gather the ZDDP level is being reduced in diesel oils as well. One possibility might be to try synthetic Rotella or equivalent and keep an eye on the engine for excessive leakage.

I frankly am not concerned about "poisoning" the catalyst in this car as replacing the converter is much cheaper and easier than engine repairs. I did this a couple of years ago when the original converter casing cracked, the new catalyst was only about $125 and was an easy bolt-in fit.