oil for GM 3.8 series II
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5w30 and 10w30 are virtually the same in terms of weight for most oils just the flow properties are different. You can substitute it just fine...
What year model is your 3.8? I had a Pontiac Grand Prix for a company car that recommended 10W-30 in its 3.8 and when I tried 5W-30 I had oil consumption. I went back to 10W-30.
One of my High School teachers used to have my dad service her 3.8 GM something... Can't remember and he used 5w30 in it without consumption issues...
5w-30 is just fine. I've been using it for the past 30k miles with no troubles.
Have a 2000 Buick 3800 Series II SC (now 75,000 miles) and it also has the 10W30 on the cap. However, I was getting a slight rap/knock with the 10W30 Amsoil so I went with a 50-50 mix of Amsoil 10W40 and the Amsoil Series 3000 5W30 for around a 7 1/2 W 35. it has eliminated the rap etc and no change in the MPG (still about 30 on the highway and 20-23 around city) so I have had this mix in for a couple of years now.
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I always used a dino 20W50 in my `87 Toronado`s 3800. I drove the living heck out of that car and it had a lil over 300,000 miles when I sold it. Engine didn`t ever use or leak a single drop of oil. Best engines ever made imo.
Either or will be just fine.
I have a 96 Pontiac Bonneville, second model year with 3.8L II. Just passed 177k this week and I used 5W30 of any synthesis on sale for the last 55k. Car runs happily at 135 miles/day, 
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I believe the last generation Series III 3800s spec 5w-30, and they are essentially identical to the Series II for oil purposes.
I run 5w-30 winter, 10w-30 summer in ours. It does consume a bit more with 5w-30 though.
I run 5w-30 winter, 10w-30 summer in ours. It does consume a bit more with 5w-30 though.
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Originally Posted By: aquariuscsm
I always used a dino 20W50 in my `87 Toronado`s 3800. I drove the living heck out of that car and it had a lil over 300,000 miles when I sold it. Engine didn`t ever use or leak a single drop of oil. Best engines ever made imo.
It's funny you say that, the '87 3.8L basically had the "turbo" bottom end minus pistons so you pretty much couldn't break it in NA trim.
I always used a dino 20W50 in my `87 Toronado`s 3800. I drove the living heck out of that car and it had a lil over 300,000 miles when I sold it. Engine didn`t ever use or leak a single drop of oil. Best engines ever made imo.
It's funny you say that, the '87 3.8L basically had the "turbo" bottom end minus pistons so you pretty much couldn't break it in NA trim.
I have used a variety of oils in mine, didn't notice a difference in any. I usually run 5w30 for simplicity. With the 3800 you usually can't go wrong. I have never heard a 3800 with "piston slap" Any noise they make usually comes from a worn timing chain tensioner.
I ran a 99 lesabre and an 00 firebird with this engine. 10/30, 5/30, 0/30, synthetic, dino, it really made no difference. I would buy based on price, climate/season, and anticipated driving style.
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Like I`ve always said.......GM`s biggest mistake ever,discontinuing the 3800. BEST engine on this planet!
Originally Posted By: aquariuscsm
Like I`ve always said.......GM`s biggest mistake ever,discontinuing the 3800. BEST engine on this planet!
That's the problem... They are out to make money by selling new cars and new engines... Cars/Engines that last forever are great in the beginning but then you have nothing but parts to sell!
Like I`ve always said.......GM`s biggest mistake ever,discontinuing the 3800. BEST engine on this planet!
That's the problem... They are out to make money by selling new cars and new engines... Cars/Engines that last forever are great in the beginning but then you have nothing but parts to sell!
Originally Posted By: aquariuscsm
Like I`ve always said.......GM`s biggest mistake ever,discontinuing the 3800. BEST engine on this planet!
If they would have taken the gasket and EGR stove pipe issues seriously, these engines would last 500,000 miles easily with lackluster maintenance. By lackluster, I mean never looking having to worry about the coolant level, averaging 5,000 mile oil changes with the occasional 7+ thousand mile oil change etc.
The antifreeze in the oil, all be it as trace amounts in most cases, has to shorten engine life.
It's a shame. I feel guilty for being a bean counter, but if I counted the beans at GM, I would have quit in protest because they didn't take into account the negative publicity from allowing basic and elementary design flaws to continue for decades.
Like I`ve always said.......GM`s biggest mistake ever,discontinuing the 3800. BEST engine on this planet!
If they would have taken the gasket and EGR stove pipe issues seriously, these engines would last 500,000 miles easily with lackluster maintenance. By lackluster, I mean never looking having to worry about the coolant level, averaging 5,000 mile oil changes with the occasional 7+ thousand mile oil change etc.
The antifreeze in the oil, all be it as trace amounts in most cases, has to shorten engine life.
It's a shame. I feel guilty for being a bean counter, but if I counted the beans at GM, I would have quit in protest because they didn't take into account the negative publicity from allowing basic and elementary design flaws to continue for decades.
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