GM 8.1 /Synthetics

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Jul 26, 2003
Illinois, USA
I just got new truck w/8.1 GM v8. At 5000 miles I want to switch to a syn oil. Owners manual limits to 5w30 or 10w30,what the best oil for every day use and weekend boat tow,7000 lbs.Also whats best filer, Delco 454 standard. LILGUY


2d I'd have no problem switching at 5K and I would DEFINITELY go with the 10W30 over the 5W30 and with a K&N filter. With your motor I would want the heaviest duty filter I could get. Someone might even recommend a filter like a Donaldson or a Baldwin and I would give that serious consideration.
I have used M1,Syntex,and Amsoil over the years.I have a friend w/a Redline franchise.I will be using the Oil Life Index computer in the truck.4 to 5000 mile est on changes.If there is a better oil please let me know,GM has issues with piston slap and I want the best lube possible from the get go.
Would you please expand on the filter question a little,I have read that Mobils filter is very good but I could not cross reference from Delcos 454.The others you have mentioned I donot know anything about.Thanks LILGUY
I tried to match my recommendations to the type motor you have...I consider an 8.1L V-8 a super heavy duty application and I wanted to recommend oil and filters more than equal to the task, not just good enough. The Mobil 1 filters are well-built and have a great filtering capability but I think they are more restrictive in terms of oil flow. Would I use them, yes, but I think you can do better. The K&N is well built, is burst resistant to higher pressures and I believe has a better flow rate. I have never used a Donaldson but my understanding is they are well built, only experience about 1 PSI differential between input and output pressure and are designed for long change intervals. I think they would be great in an application such as yours. They are available through truck/industrial equipment parts places. Since I posted my first answer, I have decided that Mobil Delvac 1 5W40 might be a good oil for you...if it complies with your warranty requirements. I would definitely consider it if warranty were not a player. While it is a diesel oil (your motor is a gasser, right?) I think it might be perfect for your application, again assuming it meets your owner's manual viscosity recommendations while you are under warranty.

[ July 28, 2003, 12:03 AM: Message edited by: pscholte ]
I also have an 8.1L Vortec gasoline V8. It is a 496 CI engine (commonly confused with the 502 crate engine GM sells). It is the replacement for the 7.4L V8 (454) and apparently it is a stroker 454. Most of the internal components have been changed so you would have to buy new parts to repair or hop it up. The filter Delco 454 seems to have the same base and thread as the other small and big block filters used on Chevy 8's over the last 30 years or so such as the 305/350/454/and 6.2/6.5 diesels. But K&N does not reccommend an oil filter for it yet. I use Amsoil ATM 10W30 since about 1500-2000 miles.
I did a cursory search at: Baldwin, Fleetguard, Wix and Donaldson. Was surprised not to find a cross-reference to an extended-service filter under the following lines:

BALDWIN: "HPG" (High Performance Glass)

FLEETGUARD: "Stratapore"

WIX: [?]

DONALDSON: "Endurance"

Of these, the Stratapore/Endurance would be my first choice, followed by the HPG. If some phone calls don't reveal a cross-reference for the longer of two fitlers spec'd for that vehicle (assuming ground clearance isn't a problem), then I'd go with any of the above brands in the size recommended. K&N, too.

I'm in agreement that low restriction to flow is more important than smallest particle capture; the reason I changed away from Mobil One filters.

I would also choose oil based on availability; the Mobil DELVAC 5W-40 or Mobil One 15W-50. We have a 3/4 ton 1987 454-TBI Suburban (TH-400 & 3.54 gears; factory oil cooler & aftermarket trans cooler) that has been pulling an 8000-lb Silver Streak since new, in every condition and terrain. Conversion to 15W-50 was at about 130k, and oil usage dropped dramatically and stabilized. Truck now has in excess of 190k with only a timing chain replacement. Filters are changed every 3000 and a complete OFL is done at 6000.

I'd also like to recommend the use of FUEL POWER.

[ July 28, 2003, 11:21 PM: Message edited by: TheTanSedan ]
I would recommend Mobil1 10w30. Its a very good synthetic, complies with your warranty and is easy to find at wally world in 5 qt. containers, currently $18.88 here. I like AC/Delco filters for a GM product. Sounds like a cool truck!
on the 2001 silverado with 8.1L you were stuck with the tiny filter on the 4 wheel drive models due to clearance to the front drive shaft, on the 2WD you can use 454 filters, like AC delco PF1218, I used UPF1218's but I think those are now discontinued. and larger 2 quart filters also fit but I never found one with a ADBV

dont know if there is any diffrence for 2005,

watch out for piston slap and bearing wear. if you are in a warm climate go thick.
Use the recommended oils and Delco filters through out the warranty at recommended intervals. This way if there is a warranty claim the oil and filter will not allow G.M. to back out for that reason .
I use the A/C delco 454. The oil capacity in the 8.1 is 6.5 qts.I put 7 qts in mine and the oil level is right to the full mark on the dipstick. I run 5 qts of M1 10-30 and 2 qts of M1 15-50.

The M1 10-30 is a thin 30wt,and my truck uses some oil if I don't add the 15-50 to the mix.
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