Question 1: I was told by a dealer mechanic that if you use synthetic oil, even though it is better(why?), it should still be changed at the regular interval. Why?

Question 2: Why is the interval on the 850, 5000 miles, versus the recommended change of 2500 (3 months) by everyone else? I don't understand this?

I have been using non-synthetic, about middle of the line oil for all my changes at 5,000 mile intervals like the manuel says. I take the car in for 10,000 mile maintenance. Stuff I can do myself, I do myself.

Thanks

Rick 97, 850-R, 55,000 miles

Well, the oil I decided to use is Valvoline 5w-40 pure synthetic @ $4.40 qt. Valvoline has a good product and name. Nobody ever mentions it though. I have yet to notice any difference. I think Amsoil is too expensive(for my taste) even though it may be the best oil made.

I do appreciate all of the advice! Thanks

No leaks, runs great. 56,000 miles Knock on wood.:-)

Rick,

Not sure on what you deceided, but I have a '95 850T that only uses CASTROL GTX. Tranny fluid, too. I've never been that impressed with Synth oils. Never felt/observed a difference between the two.

Castrol works great in the 850. FYI, Castrol GTX is a mixture of petroleum oil and soy bean oil. That's what my mechanic told me. Thanks to the soy bean, this oil has a higher tolerance for heat and less breakdown.

Volvo has always made a strong engine which can withstand more. Just remember to change the oil regularly, but not to go over 5000 miles. Doesn't hurt the motor one bit.

"FYI, Castrol GTX is a mixture of petroleum oil and soy bean oil. That's what my mechanic told me. Thanks to the soy bean, this oil has a higher tolerance for heat and less breakdown."

Is this true?
--
www.fidalgo.net/~brook4

Yes synthetic is higher quality than dino oil. HOWEVER, if you don't live in very extreme temps, and you change dino oil every 3,000 miles, you probably won't notice any difference and still get 300,000 miles out of your engine (or more depending on how you drive). I got 270K on my VW on dino and when I sold it it ran like a top and didn't burn any oil. I tried synthetic (mobil1), but I am going to go back to dino and just change more frequently--but I don't doubt it is higher quality oil.

db

As an Amsoil dealer I am quite biased toward synthetic oil, and of course the superior base stocks and matching additive packages used by Amsoil. (I consider this to really be the best oil made). On the other extreme are the really cheapie multi vis (20W-50) oils - made "thick" with viscosity enhancers and "thin" to pour in semi-cold weather with pour point agents, aka solvents - neither of which really should be "in" your engine, and indeed break down rapidly or evaporate off.

Here's how I now "look" at oil - in my 1985 245Ti at 225,000 miles - I do 10,000 mile oil change intervals - and every so often get the oil analyzed ("looked at" ha-ha) - and the oil is still good to go....neither dirt, wear metals nor breakdown products are elevated - yet I change the oil anyway, because I like to! BTW this car uses zero (0) oil and has no leaks.

My NA 855 I go 15,000 mile intervals and the oil is still almost like new.

Both cars I change the oil filters at around 5000 mile intervals (and top the oil up)

Answer 1. Many synthetics are made with synthetic base stock(s), using the same additive package that are used in the non-synthetic oil. As a result, while they are usually considerably better than the non-synthetic, they should probably not be used for extended drains without using oil analysis. On the other hand, any of them should be fine for the auto manufacturer's recommended drain interval. The only oils (that I know of) which carry recommended extended drain intervals are AMSOIL and Redline. Both of these are capable of doing as advertised. (You may consider this biased, since I've been using and selling AMSOIL for almost 25 years now--and using extended drains.)

Answer 2. You have to keep in mind that Volvo drain recommendations are based on European oil specs, which are considerably more stringent that the American API specs.


Synthetic is far superior to non-synthetic in many ways--better protection, less wear, cooler oil temperatures, less oxidation (self destruction), easier winter starts, and maybe even a bit better fuel economy.

My '96 850GLT has 97K miles, all on dino. Can I switch to syn now? I have always heard that this is risky with an engine seasoned with dino oil, i.e. leaks occur. Also, I don't drive more than 40 miles/day. Will I get the syn oil hot enough to drive off the volatiles and reap the benefits of the synthetics?

TR

If your car has been driven for an extended period on mineral oil, you should drain it, change filter and fill some cheaper mineral oil and special engine flush additive. I am sure somebody here can give you a good advice. Run this as specified by the additive producer, then drain, change filter and refill oil again. I think I refilled and drove on cheaper oil for a few hundred kilometers before finally switching to Mobil1. You will be surprised with the huge amount of junk that comes with these drainings! (It was my previous car, an Opel Ascona -87) My 850 -96 was always driven on synthetic.

synthetic oil is better and worth the money. change it ever 5k miles. use mobile 1 synthetic 10W-30 or 15W-40 if u live in the MT's or race the car for prolonged times. synthetic oil is awesome, it has multiple attributes and is probably best for our turbo cars.

I'll second what everyone else says. The reason your dealer recommends normal change intervals even when using syn oil is probably due to perceived warrentee issues (though you are out of warrentee), and he likely assumes that you will use an off-the-shelf synthetic like Mobil 1, etc. that have standard additive packages. When you use Amsoil, Neo, or Redline, you can indeed extend the interval safely. I go about 23K miles on Amsoil 10W30 in my Jeep, and about 10K miles on my S70 T5, and one year on my Volvo-Penta boat engine, with no problems what so ever. I always do an analysis on the Jeep and Volvo, and they always turns out fine.

Premium syn. has superior and expensive additive packages that give them long term durability. They generally have a very high Total Base Number, indicative of the oil's ability to neutralize corrosive combustion byproducts; lots of dispersants, to keep pollutants in the oil and not on your oil pan; lots of anti-wear additives, etc.

A major benefit of using synthetics in your Turbo is that true synthetics are very heat stable, and will not coke in the turbo. For the longevity of your turbo, this is very important. In my previous 740 T, even after 190K miles, the turbo operated like new.

I highly recommend you switch to a good syn. like Amsoil, which, based on my researh is the best. Mobil 1 is also very good, but will require standard change intervals. You can order Amsoil straight from their web site, or better yet, order it from one of our forum dealers.
--
1999 S70 T5

I use Mobil 1 5w30 in my 855 t, and only loss between 5k changes has been turbo return line! Never used a drop, and I get better mileage than with dino oil. Did run dino in this car for first 40k, but have switched, and notice the difference.

Thanks to all responses!

I decided on using Valvoline 5w-40 full synthetic at $4.40 qt. I did not do a flush. Just changed the oil as normal. No oil leaks since then. Runs great.