Switching to synthetic to utilize GM OLM - Any recommendations?

Messages
111
Location
Levittown, PA
I have a 2005 4.3l Silverado which is just coming out of warranty. I have put almost 36K miles on the clock in slightly less than 13 months. During that time, the oil (Havoline 5W30) was changed religiously between 3000 and 5000 miles. I have used the maintenance doses of Auto-RX during each oil change (3-4 oz.) The OLM (which I hadn't planned on following) first went off at 18K miles - no kidding! This was 6 months after I bought the truck with 0 mileage, which gives you some idea of the amount of highway driving I was doing. By that time, I had 4 oil changes in the can (I was keen to stay on top of the changes simply for warranty purposes.) The OLM went off again at 27K miles. The truck currently has 35K miles on the clock. Now that the truck is 1K miles away from being out of warranty, I am planning on switching to the OLM for recommended change intervals. Does anyone think I should switch to a synthetic for these grossly-extended periods? I will continue to experience the same level and amount of highway miles for the forseable future, and I also realize that the OLM is calibrated for dino oil at the specifications listed in the owners manual, but would it make better sense to spend some extra dollars on a better-quality synthetic (like Amsoil or Pennzoil Platinum) and long-life oil filter, and do a periodic UOA? This would result on forgoing the use of Auto-RX, I would assume.
 
Messages
2,435
Location
Mizzou-land
The GM OLM has a fairly good reputation and should be applicable to all GF-4, GM4718M, 5W30 oils. If you think that the OLM is faulty, get it to the dealer before the warranty runs out! If not, then keep in mind that the OLM was designed for the specifications, not base oils.
 
My OLM goes off at around 7K miles, and I'm not too keen on running a dino that long myself. I've ran it the full "OLM time" a couple times before, but that was with GC. If my OLM constantly went off around 18K, even with easy highway miles, I'd still probably do like BTJ said and go with the M1 EP.
 
Messages
4,009
Location
Calgary Canada
Why not run the M1 EP out until the OLM goes off. Then do a UOA and find out for sure. After 1 or 2 UOA's you'll sleep well at night knowing you can rely on that OLM.
 

Vortec_4300

Thread starter
Messages
111
Location
Levittown, PA
I currently have 4K miles on the dino Havoline 5W30 that is in the truck right now, so I will change that out in the expectation that the OLM will be going off sometime within the next 5-7K miles. I'll also use up the last of my Auto-RX (I have enough for one final maintenance dose.) My truck burns absolutely no oil whatsoever (if it does, it is not noticeable at all from a weekly examination of the dipstick.) Since this means that there won't be an opportunity to add top-off oil, I am going to put the best quality synthetic oil that I can find in my truck. I have some time to decide. Thanks for the advice about Mobil 1 EP - I'll definitely check it out.
 
Messages
7,775
Location
Oklahoma
I guess all programs are not the same. My 06 Accords OLM went off around 7K or so. Wow, 18K, that would make me a little nervous to trust it.
 
Messages
1,027
Location
East Helena, Montana
I wonder if there's something wrong with the OLM. No way I'd run any dino oil (or for that matter any syn oil other than Mobil 1 EP) for 18,000 miles. If you plan to change the oil when the OLM tells you to I'd run Mobil 1 EP, especially if the OLM continues to tell you to change at anywhere near 18,000 mi. intervals. And I'd do a UOA on the first run of Mobil 1 EP.
 
Messages
5,785
Location
Dixie
Any ACEA, "A5/B5" or "A3/B4" quality synthetic - regardless of basestock type - will work fine with the OLM and give you plenty of safety margin.... The main thing to watch for in GM engines is intake manifold coolant leaks, which aren't part of the OLM algorithm. [Frown] I'd test the oil in any GM engine at least annually, to make sure you aren't getting any abnormal contamination.
 
Messages
2,533
Location
Pittsburgh, PA
I ran a mix of M1 and M1 EP in my dad's Cadillac (dad wasn't paying good attention to the labels when he bought it) ran the OLM down to 6% which was about 12k, and the UOA was great. I should mention that Caddy Northstars hold 7.5 quarts.
 
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