03 Monte 3.8L Dino or Syn?

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Feb 14, 2004
I bought a dealer demo 03 Monte Carlo ss.It has the 3800 series 2 v6 engine.The car had 6900 miles on it when i bought it.First oil change with dino was at 3000 then when i bought the car at 6900 i used 5w30 Mobil1.I changed the oil at 14,400 miles and used Amsoil 5w30 this time.Last two changes i used the longer pf52 style filter.The car has the oil life system on it and it never came on before i changed the oil.I have read this site for a while and have seen good uoa reports with this engine going around 10,000 miles with synthetic.I have 6 quarts of Amsoil 10w30 and a 5 quart jug of Mobil1 10w30 to use up or get rid of.If i stay with synthetic i will continue to use Mobil1 and Purlator Pureone filters.The 5 quart jugs are like $19 bucks and the filters are like $4.So $23 oil changes.If i go with dino it will probaly be Havoline like about $1.20 a quart and Super Tech filters for $2.So about $8 oil changes.I change my own oil and do my own service work if i can.I drive 25 hiway miles to work and another 30 miles back home.About 5 of those are city miles since i have to make a stop on the way home.I plan on keeping this car probaly 5-6 years.So i am figuring at least 18,000 miles per year.If i stay Synthetic it will be 2 oil changes a year $46 bucks.If i go dino it will be 3 oil changes around 6000 miles for $23 bucks.I cant convince myself to use Amsoil only once a year.Just too many miles on a oil for me.What i am having trouble with is convicing myself to stay syn or go dino at next oil change.What do you guys think and or recomend?Am i wasting money useing syn since i most likely wont keep the car long enough?I also changed the trans fluid to Mobil1 synthetic atf and added a trans oil cooler when i bought the car also.
Hello fellow Monte owner!

First let me say that I've never used a Synthetic oil in my Monte before, but if I had the opportunity that you do (I got my 1997 a year and a half ago when it had 114K miles, it now has almost 138K) I would have started it off right with Mobil 1. Beyond the fact that I'm a believer in the Syn oils for reduced wear and improved performance, I can't give you much scientific fact that its worth the money. Had my car not had so many miles when I got it (and a Fram filter *ugh*) I would have switched it over to synthetic. Instead I use Castrol GTX High Mileage 5W-30 in the winter and 10W-30 in the summer.

If it were my new car, I would go with the OCI as recommened by the onboard computer and at each change use Mobil 1 and the AC Delco Ultraguard UPF-52 filter. I think the OCI recommened by the computer is about accurate for a synthetic oil, my 1997 was the first year for the oil monitor, and if I neglect to reset it it comes on in the 4.5-5.5K range, yours may use a different algorithm as it is a much newer car, but that range seems about right for Mobil 1 to me.

I would like to say that I do, however, use the UPF-52 on my car (which has the GM 60v6 3.1L motor) and am much happier with it than I was with the PureOne. I get much less noise at startup, and it supposedly has a significantly better flow rate than the PureOne's, in addition to having better filtration. I sleep better at night knowing I've got it on there. You can get them for $6 each at gmpartsdirect.com, plus shipping. I usually order 6 at a time so the shipping doesn't kill me.
If you do not plan on keeping the car long at all synthetics are not needed. You could also comprimise. Use a good synthetic 5W30 or 10W30 in the winter and Delvac or Delo 15W40 in the warm months. This would cut your cost in half and would still provide great protection on the off chance you decide to keep the car!

Until recently the only recomended oil for the 3.8 was 10W30. All of spec.s in the service manual are still specked with 10W30 in mind. I would not use 5W30 at all in this engine if running conventional oil at some point!!! THe conventional 5W30 simply shear to badly to protect it properly!

[ February 15, 2004, 08:22 PM: Message edited by: JohnBrowning ]
I had a 2000 Pontiac Grand Prix with this same engine. Used Pennzoil 10W30 summer and winter here in Wisconsin. Changed oil every 4,000 to 5,000 miles. Traded the car in last July with 95,000 miles on it. You could look inside the valve cover and it was as clean as a whistle. Never used any oil between changes.
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