After catching wind of the oversize filters available for small/big block Chevys recently, I was curious to try one on my '85 GMC C3500. Since about 2009? I'd been running Schaeffer's 7000 15w40 on a 3,500 mile OCI, switching to 10w30 last time around and being really surprised how obvious the viscosity change was, in a good way. Now, especially after consulting the owner's manual, I thinking I'm going to lean toward a 5,000 mile OCI w/the big filters (Napa 1794, specifically) changed every 2,500. Most of the truck's miles are in 10-40 mile spurts, occasionally racking up 200 in a day with occasional heavy towing. Consumption is around 800-1,200 miles per quart (mostly attributed to old valve seals and leaky oil cooler lines) and there's 121,500 on the clock. Cost difference is something like .23 cents/mile more for the 5K+big filter regimen, but miles per quart (not counting consumption between changes) is within 10 miles difference. Any input yay or nay on the two schedules?
Little different lube regimen on my 454
- Thread starter Alex_V
- Start date
- Status
Is the Schaeffer's Oil a syn?
Are you towing/hauling with your C3500?
Well, you'll get a few different opinions here and here's mine.
With a good amount of miles per day and additional oil added every 800-1200 miles, you can easily stay with a 5000 mile OCI and maybe longer. Also, no need to change the filter early(~2500 miles). Keep the filter on as long as the total OCI, whatever this may be.
Every time you add oil(~800-1200 miles), you are replenishing the additives so, a longer OCI could possibly be in order here...I don't know! Maybe 6000 OCI???
Are you towing/hauling with your C3500?
Well, you'll get a few different opinions here and here's mine.
With a good amount of miles per day and additional oil added every 800-1200 miles, you can easily stay with a 5000 mile OCI and maybe longer. Also, no need to change the filter early(~2500 miles). Keep the filter on as long as the total OCI, whatever this may be.
Every time you add oil(~800-1200 miles), you are replenishing the additives so, a longer OCI could possibly be in order here...I don't know! Maybe 6000 OCI???
There is absolutely no benefit to early filter changes, unless, of course, you are clogging up that filter in 2500 miles. Filter efficiency increases as the miles add up, and doesn't decrease, until the media gets clogged and you go into bypass. And, if you are clogging up a big filter like that in 2500 miles, you're got other issues to address.
In our Chevy big blocks and small blocks in taxi and farm usage, there was never a 2500 mile filter change interval, much less changing oil filters in the middle of an oil change interval.
In our Chevy big blocks and small blocks in taxi and farm usage, there was never a 2500 mile filter change interval, much less changing oil filters in the middle of an oil change interval.
Ditto on refreshing the oil because of the consumption. The oil is a syn blend and I may tow a heavy load every 45 days or so, otherwise it's 30-50 miles a day 3-6 days a week, and as often as not the oil exceeds 9 months old before it gets much over 3,000 mi. I reckon under my relatively light usage it's not going to hurt to go with 5,000 mile OCI or 1 year, whichever comes first. I have no problem spending a little extra to keep the engine together because I believe it's still very healthy internally, but mid-change filter swaps are probably unnecessary especially with the big filter. IIRC, though, the manual does say something about that in the non-severe duty maintenance schedule - may be *7,500 mi. oil, 3,750 filter*, I'd have to look.
Last edited:
Big filter with more area, no need to change as often. Just leave it for one year at a time unless you go over say 6,000 miles for some reason. You'll be fine
Have you also thought about trying a high mileage version of the oil you are using to see if that helps with consumption?
Cool, Ramblejam! I've thought about changing over to MaxLife, to save a few bucks and have better availability (maybe reduce consumption, too) but I only drive it that much for a few months at a time and, since I know where the oil's going, I'm not too concerned about it. Besides, I have a continual hope I'll get a windfall and be able to go over the engine with gaskets, valve seals, carb. rebuild, vacuum hoses, etc., and hopefully cut it down to a quart every 1,500-2,000 mi.
With your makeup oil, I would even be tempted to run it out to 18-24 months or 5000 miles, which ever comes first.
- Status
Similar threads
