Hey guys, I'm about to do a much needed oil change on my recently acquired 86 K5. I have somewhere between 159,000 and 1 million miles on it. What do you folks like when it comes to a brand and weight for high milage 305? Thanks in advance!
CK5
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Favorite oil for high milage 305
- Thread starter emunstar
- Start date
Welcome to the site!
Personally, if it has that many miles, just keep it simple and try not to spend a lot in oil. Whatever WallyWorld has in 20w50. Or go Valvoline Maxlife Semi Syn in 20w50. If you want more additive, find some ZDDP bottles (zinc additive) and add one per oil change.
Personally, if it has that many miles, just keep it simple and try not to spend a lot in oil. Whatever WallyWorld has in 20w50. Or go Valvoline Maxlife Semi Syn in 20w50. If you want more additive, find some ZDDP bottles (zinc additive) and add one per oil change.
Thanks for the welcome and the information, I was planning on the 20w50 but needed some reassurance. I think I will try the Valvoline Maxlife Semi Synthetic. So far she is running good and not leaving and stains on the drive way so I want to repay her with some quality fresh oil.
thearborbarber
1/2 ton status
I have been running walmart's supertech in my sub and have been getting good used oil analysis' back on it.
Got gauges? The gauge is no proof, but there is no reason to run anything other than what GM recommended, which I assume is 10W30. Thicker oil simply takes longer to get through the motor on startup, which we all know is where most wear occurs.
If oil pressure is enough with 10W30, no reason to go with anything else IMO. Viscosity can't make up the difference caused by bearing wear. Yes, it may raise oil pressure...that's because its resisting flow more, not because it's lubricating better.
If oil pressure is enough with 10W30, no reason to go with anything else IMO. Viscosity can't make up the difference caused by bearing wear. Yes, it may raise oil pressure...that's because its resisting flow more, not because it's lubricating better.
Ignore the gauge at an idle, 0 oil pressure at an idle in a SBC is a nonissue. As long as it has pressure when the motor revs up.
10W40 would be my choice, but not 20W50. Causes more drag and windage which eats power you don't really have to spare at this point.
10W40 would be my choice, but not 20W50. Causes more drag and windage which eats power you don't really have to spare at this point.
63chevyll
1/2 ton status
Its an old tired 305.
Put what ever oil you have laying around or the cheapest and a Zinc additive and you will be fine. Don't waste tons of money.
Most auto parts stores have in stock
Put what ever oil you have laying around or the cheapest and a Zinc additive and you will be fine. Don't waste tons of money.
Most auto parts stores have in stock
That settles it
Well, you guys raise good points all the way around, I went with 10w30 Castrol that was on sale. The oil pressure gauge is not a good indication as it jumps erratically and spends most of its time almost pegged. Im guessing it needs replaced just like my fuel gauge sending unit and almost all the lights in my dash. Saturday will be a fun day of maintenance.
Well, you guys raise good points all the way around, I went with 10w30 Castrol that was on sale. The oil pressure gauge is not a good indication as it jumps erratically and spends most of its time almost pegged. Im guessing it needs replaced just like my fuel gauge sending unit and almost all the lights in my dash. Saturday will be a fun day of maintenance.
I personally use what I can get cheapest. I can buy cases of Havoline 10w30 at Sam's Club chapter that store brand oil at the parts houses so I try to keep two cases on hand. We have 5 vehicles right now plus a mower and soon a couple 4 wheelers so I always need oil.
I must be different than most, but I had my 350 rebuilt about 10,000 miles/2 years ago, and I've been running 5w30 Mobil 1 in it. Since the cost of Mobil 1 plus a decent Bosch filter is about the same as if I took it to an oil change place and got conventional oil, I consider it a wash, but I get really good oil.
Yes, you have to really pay attention to oil prices to get "good" deals anymore. Of course, doing your own oil change can probably save you a decent amount of money too. $10 in oil, $5-10 filter, 30 minutes of time. I don't trust other people working on my rigs for the most part (I can screw stuff up just as good as anyone else, for free) so I don't have much choice anyway.
Last I purchased oil (dino from Costco) I paid $1.99/qt. Unfortunately, even if I could get double the mileage out of synthetic, it doesn't justify the cost difference for me.
Did the later 350's spec 5W30? As long as it was spec'd at some point along the line, using it shouldn't be a big deal.
Last I purchased oil (dino from Costco) I paid $1.99/qt. Unfortunately, even if I could get double the mileage out of synthetic, it doesn't justify the cost difference for me.
Did the later 350's spec 5W30? As long as it was spec'd at some point along the line, using it shouldn't be a big deal.
That may be true, but I wouldn't live with it.
I was mainly talking about engines that may not be worth the effort such as a long in the tooth 305. No reason to poll it and rebuild it for something like 0 idle oil pressure.
I use 15W-40 diesel rated oil like Rotella T or Mobil Delvac in all my trucks,it is better oil and will keep an engine much cleaner than typical oils due to higher detergency...
I often find it on sale for 12 bucks a gallon,or a truck supply store I used to work at has deals on 5 gallon pails of it in Wolfs Head or Amalie brands,they had semi-synthetic Wolf Head 15W-40 for 39.95 a pail not that long ago...cant buy regular oil for that much..
I used to use 20W-50 in my older trucks with no issues too,but the 15W-40 flows better at low temps and wont starve the bearings and top end for oil as long as thicker oil will during cold starts..you can also get 10W-30 diesel oil too if you live in colder climates..SAE 30 is a good oil for a high milegae engine used in hiot climates too...in fact my 6.2 diesels say its the "prefered" weight to use above 32 degrees,but I just use the 15W-40 oil year round in them..
I often find it on sale for 12 bucks a gallon,or a truck supply store I used to work at has deals on 5 gallon pails of it in Wolfs Head or Amalie brands,they had semi-synthetic Wolf Head 15W-40 for 39.95 a pail not that long ago...cant buy regular oil for that much..
I used to use 20W-50 in my older trucks with no issues too,but the 15W-40 flows better at low temps and wont starve the bearings and top end for oil as long as thicker oil will during cold starts..you can also get 10W-30 diesel oil too if you live in colder climates..SAE 30 is a good oil for a high milegae engine used in hiot climates too...in fact my 6.2 diesels say its the "prefered" weight to use above 32 degrees,but I just use the 15W-40 oil year round in them..
COCHEV
1/2 ton status
I run Delo in all my old flat tappet rigs
wheel400
1/2 ton status
Well as far as oil goes, I like pensoil platnium for the newer rig then castol gtx for the 75 GMC..
flatblue85
Registered Member
Oil
I agree with the rotella t 15w40 in my tired 305 for a while now and no problems and the old girl seems to be happy
I agree with the rotella t 15w40 in my tired 305 for a while now and no problems and the old girl seems to be happy
4xcrazy
3/4 ton status
I used some 15-40 in an old 305 I had, because I acquired it for free, it tore my cam and lifters up, quickly, and when I removed it, it was about as thin as water.
From previous discussions on here about this, the consensus was that the 15-40 has a much greater detergent content and it must have really cleaned out the passages and whatnot, sending all the engine crud through the system, eating everything while they were going.
I'm not a fan of that grade of oil, simply because of how thin it looks when you drop it from an engine, acts like water.
Now since this was already a high mileage 305, but with a new cam & lifters, it was decided to run Quaker State 20/50, after break-in of course.
Reason, from this persons (friend) long term automotive past, it was an opinion that that oil seemed to help keep lifters quieter. Honestly, after running it for awhile, i would tend to agree.
I would switch off from Quaker State and Havoline, both seemed to work good, although I would have to say when the engine was finally tore apart, there was significant sludge and dried up oil caked on everywhere.
After serious research, I have finally decided that ALL my engines now run a full synthetic oil, usually 10/30 winter 10/40 in the summer months.
I did do a full synthetic oil change on both parents vehicles, dads had over 130k, moms 4.3 had well over 155k, both running full synthetic Mobile One with Mobile One oil filters. You could almost instantly hear the difference in the noise the engine made after the switch.
a lot of people say, you'll get leaks doing that, non of ours leak at present and even though they are already high mileage engines, i can't see what changing to full synthetic could hurt, other than help keep the engine cleaner and maybe add a few more years to it's life.
Bottom line, to answer your question, if you don't care much about the engine and plan on replacing it real soon, I'd just run the el'cheapo crap from the parts store.
Depending on mileage and climate you drive it in, I always ran 20/50 in Phoenix summers, with the extreme heat, oils break down a bit quicker in that kind of heat.
From previous discussions on here about this, the consensus was that the 15-40 has a much greater detergent content and it must have really cleaned out the passages and whatnot, sending all the engine crud through the system, eating everything while they were going.
I'm not a fan of that grade of oil, simply because of how thin it looks when you drop it from an engine, acts like water.
Now since this was already a high mileage 305, but with a new cam & lifters, it was decided to run Quaker State 20/50, after break-in of course.
Reason, from this persons (friend) long term automotive past, it was an opinion that that oil seemed to help keep lifters quieter. Honestly, after running it for awhile, i would tend to agree.
I would switch off from Quaker State and Havoline, both seemed to work good, although I would have to say when the engine was finally tore apart, there was significant sludge and dried up oil caked on everywhere.
After serious research, I have finally decided that ALL my engines now run a full synthetic oil, usually 10/30 winter 10/40 in the summer months.
I did do a full synthetic oil change on both parents vehicles, dads had over 130k, moms 4.3 had well over 155k, both running full synthetic Mobile One with Mobile One oil filters. You could almost instantly hear the difference in the noise the engine made after the switch.
a lot of people say, you'll get leaks doing that, non of ours leak at present and even though they are already high mileage engines, i can't see what changing to full synthetic could hurt, other than help keep the engine cleaner and maybe add a few more years to it's life.
Bottom line, to answer your question, if you don't care much about the engine and plan on replacing it real soon, I'd just run the el'cheapo crap from the parts store.
Depending on mileage and climate you drive it in, I always ran 20/50 in Phoenix summers, with the extreme heat, oils break down a bit quicker in that kind of heat.
4xcrazy, what are your thoughts on the high mileage oil? Beneficial, or just marketing?
I've been running Mobil 1 high mileage in both my trucks for the last 3 years and haven't had any issues, but I'm curious about your opinion.
I've been running Mobil 1 high mileage in both my trucks for the last 3 years and haven't had any issues, but I'm curious about your opinion.
4xcrazy
3/4 ton status
Haven't researched it much, I have used it, but I'm not so sure it not just an advertising stunt.
I had an '87 2wd Suburban for awhile, with an older 350 in it, when I got it the oil was nasty. I already knew the engine was going to need rebuilt soon, so I was just putting in the $2.99 O'Reily cheapo stuff. It leaked bad, burnt some, I just kept it cleanish with that stuff. Sold it off right before i moved up here anyways.
I obviously didn't use a $15 filter on it, but I also didn't use a Fram
I had an '87 2wd Suburban for awhile, with an older 350 in it, when I got it the oil was nasty. I already knew the engine was going to need rebuilt soon, so I was just putting in the $2.99 O'Reily cheapo stuff. It leaked bad, burnt some, I just kept it cleanish with that stuff. Sold it off right before i moved up here anyways.
I obviously didn't use a $15 filter on it, but I also didn't use a Fram
