My 2000 gmc sierra is leaking oil on my driveway more than normal

AMSOIL 5W-30 Signature Series 100% synthetic motor oil or Mobil 1 5W-30 Extended mileage are probably the best 2 synthetics. Depending on the mileage, you might be better off with using a standard 5W-30 non-synthetic oil and just change it regularly.

Check this information about your 1999 GMC Truck Jimmy 4WD 4.3L SFI 6cyl :

Engine Oil Type/Weight/Capacity
683690
Application:
Use in all temperature ranges
Note : Valvoline Premium Conventional 5W-30 Motor Oil 5+ Jug


98HC54
Application:
Use in all temperature ranges
Note : Mobil 1 EP 5W-30 - Extended Performance Synthetic


220013721
Application:
Use in all temperature ranges
Note : Chevron Supreme 5W-30 Motor Oil


550022689
Application:
Use in all temperature ranges
Note : Pennzoil Platinum Full Synthetic 5W-30



Hope this helps (remember to rating and leave a testimonial about this free answer).

Your oil best oil is 5W-30.

The engine on a 1996 Saturn SL uses SAE 5w-30 engine oil. The recommended oil-change interval for this engine is every 3,000 miles or three months, whichever comes sooner.
---------------- This will help.Thanks.Helpmech.

Maximum Performance Signature Series 0W-30 100% Synthetic Motor Oil (SSOQT) Signature Series 0W-30 100% Synthetic Motor Oil (SSOQT)
Drain Interval Information
Maximum Performance SAE 5W-30 Synthetic Motor Oil (ASLQT) SAE 5W-30 Synthetic Motor Oil (ASLQT)
Drain Interval Information
Performance Plus XL 5W-30 Synthetic Motor Oil (XLFQT) XL 5W-30 Synthetic Motor Oil (XLFQT)
Drain Interval Information
Performance Synthetic 5W30 OE Motor Oil (OEFQT) Synthetic 5W30 OE Motor Oil (OEFQT)
Drain Interval Information
Above 19 F......10W-30
All TEMPS......5W-30 [1]

Hello, I am a Jeep technician with 13 years of experience, I would recommend Mopar oil filters and Mobil 1 fully synthetic 5w-30 oil changed at 5000 mile intervals

ENGINE OIL

You will need to use a 10W-30 grade engine oil, such as any of the following Mobil products.
"Fully synthetic" oils are more expensive. Conventional oils or syn blend engine oils are fine for the vehicle but need to be changed more frequently.

Mobil 1 Extended Performance 10W-30
fully synthetic motor oil ;
Mobil 1 High Mileage 10W-30
fully synthetic motor oil;
Mobil 1 10W-30
fully synthetic motor oil;



Mobil Clean 7500 10W-30
synthetic blend motor oil ;
Mobil Clean High Mileage 10W-30
a conventional motor oil;
Mobil Clean 5000 10W-30
a conventional motor oil .

I've used Mobil 1 5w-30 synthetic in customer cars. You can use conventional oil with the same wieght.

Royal Purple is compatible with fully synthetic oils so you can change over with no damage to your engine. You can go to the official site and they can give you all the options as far as what your looking for specifically.

Why not? Of course it can! What could happen to (any) engine because of that? A little bit worse (1 to 3%) fuel efficiency since 5W-30 is thicker than 5W-20! But, I'd ask you right now: Why you even consider synthetic blend? If you think that synthetic part (max 30%) in blended oil is going to improve mineral part you voluntarily admit that synthetic is better. USE (FULL) SYNTHETIC and have all the benefits - better mileage, extended drains, cleaner engine, better winter start, smoother operation... Want more? Why to waste natural resources if you can have simpler and better maintenance with synthetics? Do not forget good air and oil filters! They keep engine's longevity! If you want recommendation(s) - use Amsoil (XL oil for 7500 mi) or Mobil (extended). All others are (poorer) copies of them! For the filters - again Amsoil! Absolutely better than K&N! Same air flow and 50 times (!!!!!) better filtration. (If you need more info call 519-739-3765)