I live in Homestead, Florida and am looking at a long hot summer coming up. I am about to drop the oil on my 1992 740 Wagon. The original owner claimed his mechanic was putting Mobil 1 in the motor but I doubt this. I put some Wal-Mart 5W30 synthetic oil in the motor about 5000 miles ago and it dirtied pretty quickly and deeply. I am now going to replace that Wal-Mart oil with some Mobil 1. I spotted the 15W50 and decided to give it a try in an attempt to get an extra edge against the Florida heat. Am I creating problems using this weight of oil? For what it is worth this Volvo runs hot and one of the things I am looking to deal with is that issue. I intend to switch back to my normal 5W30 around November when I drop this oil; unless 15W50 turns out to be a better weight for this motor and driving conditions. What can I expect?

I use 20/50 Castrol dino year round here in SoCal on my '89 turbo without any problems. Clean the radiator fins out with a hose, flush the cooling system and replace the thermostat. That should fix the cooling issues unless the cooling system has really been neglected and there's a blockage inside the head somewhere.

I use 20/50 Castrol dino year round here in SoCal on my '89 turbo without any problems. Clean the radiator fins out with a hose, flush the cooling system and replace the thermostat. That should fix the cooling issues unless the cooling system has really been neglected and there's a blockage inside the head somewhere.

I thought I would get back to this thread with some information about how it is going for me with this oil. I am experiencing some loss of gas milage but I am unable to say this is purely the fault of the oil. I think the ethanol in the gas is causing my milage to drop in all of my cars. As well, I usually do not run the AC but have been doing so and I do more city driving in the summer so all these factors may contribute to the loss of milage in this car. What I have noticed, oddly, is that the oil drips on this car totally stopped overnight with this oil. What is THAT about? I am thinking the 5W30 was too thin and was finding its way out of the gaskets. Am I right in that?

And have since it became available. It has the best price break of all Amsoil synthetics and if it meets your specs (it is more than spec'd for 1992) it is fine for Florida. This grade is great for heavy duty marine engines, both gas and diesel. It has a high detergent and anti-soot additive package as well as anti-corrosion for engines that sit a lot.

I change oil on the 740T every 10K. Saab 900T every 10K. Audi 4.2Q every 8500 simply because the service reminder light comes on and I run it into the dealer for their check too.

Only car I don't use it on is the E46 M3 because BMW specifies 10W-60 Syntec by Castrol and the engine is warranteed. Interestingly they have to provide the oil free (but only every 15K) if it's required for the warranty...after 50K miles it's my nickel but since the car is extended warranty to 100K and I extended the maintenance plan as well, it's all covered. I change the oil every 7500 or so, let the dealer do it on the 15's.

Why don't you use the AmsOil 5W40 Euro Oil in your M3? It meets BMW LL-04 and even VW 505.01 - Do you plan on using that once the warranty on the M3? I'll likely buy an e46 325i in a couple months and will likely use the Euro 5W40 until it hits 100k and then swap to 10W40.

I run 10W40 AmsOil in a Volvo 745T with 264k and a BMW e36 w/ 190k and they both run great. I use AME (15W40 Marine) in my '73 911 only because it sits a lot. They make great products. Do you use the gear lubes & ATF too?

Doug
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D '90 745T 229k, '88 744GLE 129k, '96 328i, '73 911T 100k+

I've used Mobil 1 15W-50 in our 1991 745 (B230F) since new, and change it regularly. Its got 201K miles on the clock now, runs like a top, and doesn't leak a drop. But the heat and sun here in Arizona has really done a number on the paint....

I'd say find an oil and viscosity which matches up with the owners manual and stick with it.

I agree with the earlier posting: the oil choice will have little to do with any overheating issues. FYI, our car needed a new (Volvo) water pump at 103K miles ,and an IPD radiator at 120K. Both are still in good shape. Typically we change the coolant and hoses every 60K or so.

Good Luck.

If you can get it, rotella 15w40 diesel synthetic is a pretty good choice and very widely used in many older gas vehicles. $16 for a gallon at wallmart most of the time. Lap tests show it's about as good as Mobil 1 stuff, and holds it's viscosity better over time. And it's cheaper.

15W40 is recommended for all temperatures above 0 F, so 15W50 would seem to be a good choice for your harsh climate conditions. 10W30 is suitable for -20 to 100 F, so that would be a good choice for winter. 5W30 is a bit thin for Florida (but good for northern winters) as it is only recommended for temperatures up to 68 F.

I have never felt the extra expense of synthetic was justified for a non-turbo B230, so I use 15W40 "diesel" oil in the warmer months, and have not noticed any sluggishness to the way the engine runs, or poor fuel mileage (I get consistently in the high 20s with a manual transmission) and I like the added protection of the heavier oil.

Herb G is correct that if your engine seems to be running hot, you should thoroughly check out your cooling system. This is not normal for these cars. They should be able to deal with any temperatures you are likely to encounter, and not break a sweat, even with the A/C on.

RE: your engine cooling issue. Let me add my $.02.

I also live in Florida, and have owned 7 Volvo's in the Sunshine State. The only cooling problem I ever had involved an '88 240 with a mis-installed timing belt (my fault), and also an original (plastic) radiator. I fixed the timing issue, and installed a METAL, 3-ROW RADIATOR (as I have done on all my 240's and 740's), and have experienced zero overheating problems since, on that car or any other. Never over 50% on the gauge in mid Summer with A/C blasting. You may as well change the thermostat and hoses at the same time.

Attend to this before tampering with lubricants...excess heat will quickly age even a Volvo engine. I had a negative experience with synthetics on an older B230 engine a couple years ago...blew the rear cam seal out at the first use of synthetic after 140k miles on petroleum oil...possibly a coincidence, but many 'old volvo hands' recommend against switching to synthetics in older engines on these cars, and I scared me off them. I try to use 20W50 mineral oil year 'round.

Good Luck.

Personally, I'd use a less viscous oil, particularly if you are running synthetic. With the price of fuel these days, any advantage you can give yourself mileage-wise seems warranted-- the extra viscosity works against you, and for no particularly good reason. As for the car running hot, I'd look to your cooling system rather than the oil. A cooling system flush and a new thermostat seems like a good idea.

Good luck!