Do you have to use 10w30?

I have used 5w30 in all my vehicles for years. I just bought a used 1998 Grand Prix GT and noticed that the cap says 10w30. Will it hurt to switch? Does it really matter? I don't want to hurt anything if the engine has to have 10w30, but I can't see why it would. Please advise....

Also, just a point of complaint, I was going to change the oil pan gasket.....WOW, it looks like you have to take half the engine and mounts off. WHAT A PAIN. Don't know if that is something I want to tackle....

Oh, and last, but not least, does anyone know the oil capacity? I didn't get an owners manual with it????

Thanks

Where do you live? If you live somewhere where the temps. get low during the winter, then I would advise using 5w during the winter. If it is warm where you live year round, use 10w year round. Otherwise, use 10w just in the summer. It is much better for the engine. Also, synthetic oil has proved to work very well in these engines. I've been running 10w Amsoil synthetic in my GT all summer.

As for the oil capacity, it is 4.5 quarts WITH filter change.

i have a gpgt2000 and live in long island new york... its time for the oil change. as of now i have regular oil in the car.. the cheep kind from jiffy lube... I want to put the synthetic stuff in tomorrow.. exactly what kind do i put in... and i dont know if it matter but i have a thrasher cai intake.... dont know if you need to know that.. thanks a lot....

I use Mobil One Synthetic w/ the Mobil One M1-201 filter

Well, the hotter the weather the thicker the oil. I live in the Caribbean(PR) and I use Motul 10w40 all year round and 15w40 on really hot summers. So as the rom states if you live in cold weather then use 5w for winter and 10w for summer. If you live in desertic areas like Texas or really warm and humid like PR I would advice to use 10w40 except on summer where 15w40 would be a better fit(I am talking about summers that could be 105degf or hotter outside). Remember the low number is more related to the oil thickness when the car is cold. THis number depends on the internal engine lubrication ducts diameter. IF you have a modified engine block like an http://www.intense-racing.com one then the oil specification might change since the engine internal lubing mechanism is different.

I have used 5w30 in all my vehicles for years. I just bought a used 1998 Grand Prix GT and noticed that the cap says 10w30. Will it hurt to switch? Does it really matter? I don't want to hurt anything if the engine has to have 10w30, but I can't see why it would. Please advise....

Also, just a point of complaint, I was going to change the oil pan gasket.....WOW, it looks like you have to take half the engine and mounts off. WHAT A PAIN. Don't know if that is something I want to tackle....

Oh, and last, but not least, does anyone know the oil capacity? I didn't get an owners manual with it????

Thanks

You can use 0w-30 synthetic. You don't have to use 10w-30.

About which oil to use: I've researched that and here goes:

I just found out the answer to that question: Chevron Delo 400 Synthetic 0W-30 if you live north of Texas, and Mobil 1 0W-30 if you live south of Texas (southern states only).

Why? Almost half your lifetime engine wear occurs during cranking (confirmed by several engineer friends and also by Mobil Oil Company), so a 0W-30 is the right weight to cut wear down. The "0W" part means the oil gets up and gets going to the bearings the fastest during engine cranking at start-up. Therefore, a "0W" is the best. (A "0W-30" can be used where the manufacturer recommends a 5w-30.)

But why Chevron Delo Synthetic 0W-30 for anybody who lives north of Texas? Taking the "Dragnet" approach, "Just-The-Facts", look at the incredible technical spec sheet at http://bestsyntheticoil.com/dealers...une-17-2003.pdf and notice that Chevron, employing some of the best engineers and having some of the best labs in the world, have come up with a synthetic oil that has a Pour Point of -76 degrees below zero. BEST THERE IS. That low number means that their Delo Synthetic 0W-30 oil resists the bad effects of cool temperatures, indicating that it is going to flow better when the weather is simply below freezing as well. By the way, the Chevron oil's Flash Point is still OK at 419 degrees (any number over 400 is good).

South of Texas (any southern state), its fine to use Mobil 1 0W-30, since its Pour Point is almost as good as Chevron's Delo Synthetic, and Mobil 1 has a slight edge on high temperature Flash Point.

Also, Mobil 1, like Chevron Delo Synthetic, is produced by world-class, well-funded engineers with some of the best labs anywhere. This means Mobil 1 or Chevron synthetic have proper additive packages in addition to having oil that flows at cooler temps and hangs in there at high temps.

One note: If racing or pulling a trailer, you might want to use Chevron Delo Synthetic 5w-40 weight or Mobil 1 synthetic 0w-40 weight. However, the 0w-30 weights in both brands of oil would probably do just fine there too. One more note about racing: Using Mobil 1 0w-20 may be the best for racing, since the lower-viscosity "20" number means it takes less horsepower to run the oil pump, giving you slightly more horsepower available to drive the wheels! Slight horsepower advantage with the thinner "0w-20" Mobil 1 synthetic, but possibly less engine life. Again, the Mobil 1 "0w-40" would make the engine last longer in racing, but it soaks up more horsepower than the Mobil 1 "0w-20" --- you choose which is more important when racing!

Chevron Delo Synthetic 0w-30 may only be available at trucking supply stores. Mobil 1 is available everywhere.

I don't work for Chevron or Mobil. I am an engineer (Mechanical/Aerospace/Computer) and I think you've got to go on the facts without ANY marketing hype.

It may be noted that Chevron sells the Delo Synthetic to trucking fleet managers who they know will see the numbers, so marketing hype is not going to suffice. That might be why Chevron has the best Pour Point while some other more heavily consumer-advertised oils don't.

For higher mileage (more than 75,000 miles) it may be good to go to Mobil 1 0W-40. Again, stick with the "0w", but in this case make the top number "40" to fill the larger clearances in older engines. I'm not completely sure about whether you really have to go to the 0w-40, and if it was me I would stick with the Chevron Delo Synthetic 0w-30 for any car in states north of Texas, and Mobil 1 synthetic 0w-30 for southern states, as in the analysis above, even for older engines.

good luck

It is a good idea to use what the manufacturer recommends for daily drivers. 10w30 is what the L36 and the L67 call for, so I'd use that in all normal weather conditions. In the worst of the winter it is a good idea to go with 5w30 for the mentioned faster oiling cold starts. You should consider using 5w30 year round on a vehicle that often goes weeks or months without being started, like an occasional street muscle car or something along those lines.

Mobil 1 is goood stuff :)

It is a good idea to use what the manufacturer recommends for daily drivers. 10w30 is what the L36 and the L67 call for, so I'd use that in all normal weather conditions. In the worst of the winter it is a good idea to go with 5w30 for the mentioned faster oiling cold starts. You should consider using 5w30 year round on a vehicle that often goes weeks or months without being started, like an occasional street muscle car or something along those lines.

Mobil 1 is goood stuff :)

The only reason the manufacturer recommends 10W-30 is because they assume you will use conventional (non-synthetic) oil. The 10w-30 has less VI chemicals than a 5w-30 in a conventional (non-synthetic) formulation. More VI chemicals can cause the oil to degrade more over time. When using a synthetic, you can go to a 0w-30, and if you read the owner's manual, that is allowed in the Grand Prix with the Buick V-6 3.8L engine.

Reading this posts makes sense to use the lower 5w on cooler temps since it will lube the engine quicker and 10w for hotter conditions because heat tend to liquify oil and even tought I was not aware that the owners manual only reffered to normal oils that these numbers are related to normal oils only.
Forced question Engine Mapper, are these oils you talking about full synthetic?
The one I use is ehter based.

Do you work for Mobil or Chevron? :iceslolan

Reading this posts makes sense to use the lower 5w on cooler temps since it will lube the engine quicker and 10w for hotter conditions because heat tend to liquify oil and even tought I was not aware that the owners manual only reffered to normal oils that these numbers are related to normal oils only.
Forced question Engine Mapper, are these oils you talking about full synthetic?
The one I use is ehter based.

Do you work for Mobil or Chevron? :iceslolan

I don't work for Chevron or Mobil, nor am I an engineer in the oil industry. (I've worked in the aerospace industry.)

The Chevron Delo and Mobil 1 are full synthetics, and I think both are PAO-based.

The 10w number you speak of is only at low temperatures. The other number is for hot temperatures. The wider the range the less the oil will thin out as it gets hot. A small lower number, like "0w" is better, and the upper number, like "30" means it does well at high temperatures.

You got that right. In my case I have always used 10w40 synthetic or not and have not had problems. My Z-34 has 193k on the odo and the GTP well that is another story. This is the second engine that Y blow