Picked up a 99 C5 with 92k miles a few weeks ago and wanted to inquire here about your experiences with Seafoam on C5's. I was considering doing the trifecta of gas, crankcase, and throttle body cleaning with seafoam, then changing fuel filter, plugs, and oil.

Any thoughts or comments regarding this specifically?

 

What issues are you trying to fix with using sea foam?

 

Nothing specific; just looking for a deep engine clean. My fuel gauge stops working on occasion, and figured it would be good anyway as I approach 100k miles.

 

id just leave it the way it is. Sea foam and the sorts do more harm than good. Techron may correct your fuel gauge issue but the true issue can be corrected with new fuel senders.

 

Agreed!

 

I would forego the crank case cleaning and just run the techron or SeaFoam in the fuel tank to counter the gas gauge issue. I've run SeaFoam and Techron in the gas tanks of all my toys and equipment and contrary to statements above I haven't had any issues.

In fact I run them through my 1929 Model A barn find (still all original and still running since 1929). I run them through my 1985 Vmax 1200. Still running like a scalded ape since 1985. I run them through my C5 and 6 other vehicles. As well as my power equipment.

The C5 gets more treatments than the other vehicles to prevent the fuel gauge issue. I've had this C5 since brand new (1999) and the gas gauge issue started occuring in 2003 (only using Chevron fuel). Until I learned to run Techron or SeaFoam through the tank a few times a year. Only using Shell since 2007. The issue practically went away since 2003. Until recently when I had to get fuel from an off brand station in an emergency situation. Two cans of Techron or SeaFoam (depending what I have on tap in the garage) since and the issue has yet to come back again since June 20th 2021.

SeaFoam also fixed a sputtering issue I had in a 2004 F150. Only Shell gas. New plugs and wires yet the truck would sputter and breakup over 75mph in OD. Added a can of SeaFoam to two full tanks and issue was resolved.

I subscribe to both Techron & SeaFoam and I've only had positive experiences with both products.

 

I've used both products with no issues at all. They do exactly what they're advertised to do, something damn few other products can say........

 

Agreed, grinder. I never believed in the Genie in a Bottle voodoo before. My brother in law restores antique cars and tractors as a hobby. He has 40 or so tractors from the 40's, 50's, 60's, 70's and 80's. And 6 or so hot rods and muscle cars. He turned me on to SeaFoam and a forum member here turned me on to Techron about 20 years ago. All my and his machines and vehicles purr and it's definitely no thanks to ethanol in the fuel, or over obsessive maintenance practices. At the very least SeaFoam and Techron helps to keep injectors clean, carb JETS clean, and sulfur deposits on the fuel sending units at bay.

 

You guys really know how to review a product. Gonna pick up some of that stuff…and maybe some beer too.

 

Good call. The "medicine shop" is usually my first stop on my way to the Advance Auto in town. Once I pop tops I don't drive though. So it's always a conundrum on the weekends.

 

I do add Techron to my cars when I take a long road trip. I also add it to my kids cars when they come home from college for a visit. Cant hurt thinking.

Our intake manifolds build up a lot of oil. If you use a catch can, that will reduce the amount of oil that builds in the manifold. I found spraying seafoam into the throttle body directly into the manifold is VERY effective removing that build up, but adding it to the gas tank doesnt.

Spray it into the manifold during idle and some light revving and let it sit for 30-45 minutes, then going out for a drive will burn off some of the pooling oil building for years in the manifold effectively.

I think of it this way. If you have a lot of oil pooling in your manifold from normal use, Your Air Fuel Ratio at WOT becomes Air Fuel Oil particles Ratio and can promote timing reduction. Again, it cant hurt cleaning the manifold.

 

I add a can of Seafoam to the gas on daily drivers every 25k miles. On the Vette, which does not get driven a lot, 1/yr. I would not add it to the oil - modern synth oil is extremely clean and will actually clean out old dino oil deposits. I saw this with my own eyes on my wife's DD Mazda - owned since new - premium dino oil changes every 3k till 100k - some sludgy buildup on the head - switched to M1 and all the sludge disappeared within 10k

The Seafoam corrected fuel sender issues on both Vettes, and fixes minor stumbling / cold start roughness on the DD's. I suspect it's cleaning crap off the injectors. I also clean the TB on the DD's every 25k.

Seafoam / techron / Redline, I think they are all pretty similar, Naptha iirc is the active ingredient.

I use it on the lawn equipment too - really makes an enormous difference keeping 2-stroke equipment running well. I used to be very skeptical; dismissed it as 'snake oil'. I had a 2-stroke Stihl trimmer running like crap, just could not get it to run well. Nothing to lose I figured. Couple ounces of Seafoam in the gas, ran it hard, sucker smoked like a mother and started running good as new. Night and day difference.

 

I have been using Techron for the last year with no luck on fixing the fuel gauge issue. Was told by guy at auto zone to use sea foam it’s the best but haven’t tried it yet as the weather has been so crappy since waking it up and only put 40 miles on it this spring so far. Hopefully it will work

 

Unfortunately, you'll likely net similar results from SeaFoam to Techron. Which in your case you may not be dealing with a sulfur buildup and your sending unit may just be shot. In which case you'll likely need to replace the sending unit to remedy the issue.

Running top tier fuel brands, 93 octane and running techron or Seafoam is preventative. And will reverse the issue in some cases, as it has for me since 2003. But if you have a parts failure the results won't improve with treatments.