3300 (LG7) Buick Fireball V6 Engine...
I recently acquired a nice old 1993 Olds Ciera S which has a Buick 3.3L V-6 engine. Having run a 1996 Ciera SL until it disintegrated from body rust, I figured the retired Ciera SL would provide a variety of usable spare parts to keep the Ciera S going. There are considerable differences between these two vehicles although a lot of parts are interchangeable.
My first surprise was that the Buick motor explicitly called for 10W-30 API service spec rating SG motor oil. The Ciera SL was not explicit on service rating but called for 5W-30 with the API starburst on the container.
The Ciera SL just had SAE 10W-30 on the oil filler cap but the Ciera S with the Buick 3.3L had SAE 10W-30 and API service SG on the oil filler cap.
Looking in the operators manual, the 3.3L motor was said to be ok with 5W-30 if ambient temperature was below 60 degrees F.
Looking all over the internet, I got the impression that the difference between OW-30, 5W-30, and 10W-30 was quite little. Amsoil claimed that their 5W-30 was 59.5 and 11.7 centistokes at 40 degrees C and 100 degrees C respectively and that their 10W-30 was 66.1 and 11.7.
Thus at operating temperature, both Amsoil oils had the same kinematic viscosity but at lower temperatures the 5W-30 had better flow. I didn't get into the sheer comparisons but they may be a big deal at low temperatures although getting the oil to flow regardless of sheer could beat that argument.
Further reading pointed out that the most recent API rated oils with SN service ratings may not be good for older engines with flat tappet camshafts as opposed to roller cams since the SN rated oils may have less ZDDP anti-scuff additive (zinc dialkyl dithio phosphate) which could lead to cam/lifter scuffing trouble.
Since this Buick 3.3 L motor is standard and with no modifications, I am wondering if going to 5W-30 API SN service rating oil is reasonable since I don't beat the crap out of the car and am a hyper-miler driver attempting to squeeze ever MPG possible out of each fill up?
Any comments or insight would be appreciated. I have never experienced a lubrication related problem on any car I have owned and I drive them to extinction which generally means that the body falls away to the extent that repair of any sort is futile. The engines and non-structural mechanical parts have always gone to the salvage yard in great shape as far as I know.
according to my local engine builder, a stock flat tappet engine that has 20k miles or more is almost always safe from scuffing without additional zddp.
its trying to break a flat tappet engine in without zddp that eats cams.
as for hypermiling, a fella that stops by to chat regularly sez his numbers went up noticeably when he went to synthetic oil...
Thank you for the comment on the ZDDP at under 20K. This Buick 3.3L V-6 has 60K and appears to have been taken care of quite well by an old couple.
I suspect that synthetic oil would improve the gas mileage and I'll note any improvement I get from the change to 5W-30 from the 10W-30.
the newer oil without the zinc is a deathwish in a flat tappet cam.
your engine builder going to rebuild your 22k mile flat tappet camed engine when the cam goes flat? as it wipes the cam and valve tips and rockers.. all parts that require the zinc and when without it, open up the lash on the valvetrain preload.. as all these part wear?
next up is man made oil.. flat tappet cams REQUIRE some friction to spin the lifter.. the syn oil remove that.. a lifter that doesn't spin goes flat ..
g.m. engineers know a little more than that machinist..
if there wasn't a reason for spec'n an oil they'd not waste the time or the dollars doing so..
Given that the original oil spec for the 3.3L V-6 was 10W-30 SG, and I went to 5W-30 SN, where would you say that I stand? I expected to use regular petroleum oil and was ok with the viscosity difference but did read that the ZDDP on SN spec oil may have lowered the ZDDP. The SN spec supposedly covers the now obsolete SG unless I don't understand the rating system or the oil dudes aren't telling the complete story.
I know there are additives to bring up the ZDDP but most things I read moan about affecting the overall oil performance by screwing around with additives. Since SG is an obsolete spec now and was superseded by SN, what would you run in a 3.3L V-6 with flat tappets?
The typical person in such a case might just move on to 10W-30 and get the SN spec standard oil unless it were pointed out to him that some other grade with a better ZDDP level were known.
What would you run in this motor given that it is driven in a moderate way and has no modifications and has 60K miles presumably having always been run on 10W-30 SG?
Thank you for the tip on lifter spin. I suspect the oil spec dudes roll in a lot of trade-offs and don't presume that too many people are still messing around with older cars or actually using them to get from point A to point B.
If your really concerned about what oil to use. Use 10W30 Shell Rotella T5 diesel oil. Semisynthetic or synthetic wont hurt anything. Many flat tappet engines are running synthetics. Oil technology has changed. synthetic was not mainstream or well known in 1996 tho it did exist
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