Is there a real diffence between different brands of non-synthetic oils? Any brand that has actually tested better on a long-term test? I vaguely remember on consumer group doing a taxi testing for 1 year and 3000 interval oil changes and seeing no real differences, but that's not what long-term and lacks significant start-up engine wear.

what about putting deisel grade engine oil in a gas engine?

 

Wow. Okay as long as the non-synthetic oil meets the manufacturer's requirements(usuall api or sae) it's all the same stuff. Doing regular oil and oil filter changes by FAR MAKES MORE DIFFERENCE THAN THE BRAND OF OIL YOU USE.

If you are really into superior engine protection, look into synthetic oil like mobil 1, amsoil, redline, royal purple etc.. Again for the most part, all synthetics are basicly the same.

Don't put oil designed for deisel engines into an engine designed for gas.

 

mostly in their additive packages; i.e. what a manufacturer combines with the oil to keep the oil from degrading over time and thereby not protecting your motor as well.

If your bent on non-synthetic, <A HREF="www.ulx110.com">ULX-110</A> is the best stuff that I have been able to find. It has extended drain interval (up to 15k) and runs $4 a quart....

If you tune back in the first week of January, I hope to have lab results of ULX-110 oil in my 99 Maxima, which has been in for over 10k miles. I do have a full 2-1/2 gallon container of ULX-110 which I am going to sell once I have these lab results....

However, I am switching to Amsoil synthetic oil next time to go 25k without changing the oil, and 12.5k without changing the Amsoil oil filter...Use the handy search feature and type "Amsoil" and you should find all sorts of nonsense posts by Jeff92se and myself praising it.....

Jeff is right. Changing the oil every 5k AND the filter with name brand stuff (other than Fram oil filters) will yield good protection for your motor....

 

I change oil filter and oil every 3,000 to 4,000 miles depending on the driving conditions. On the Max, it's 3,000 plus or minus 200 miles. The reason I ask about the diesel engine oil is that some brand (e.g. Valoline) have ones that are rated for both gas and deisel. One VW/Audi mech. said that Cen-pe-co a premium paraffin based oil gives almost no sludge even after over 100,000 during an overhaul, while some of the popular brands gives lots of sludge and build-up. His rating was Cen-pe-co > Rotella (also paraffin based) > other brands based on the sludge accumulation and quality of the base oil. He also claims that the popular brands are mostly "asphalt based." In the oil days they got the good grade oil from mixture of mineral oil and cracking of paraffin, so the color was clear. I also noticed that they smell different, kind of a sweet odor.

The Rotella is slightly more expensive than reg. brand oils. The Cen-pe-co much more (2X). Synthetic is lots more 5X. Synthetics use different bases, I forgot which one Mobil 1 uses but think it's different from Amsoil. Since I change oil every 3K miles, I don't think the synthetic route is for me. The oil analysis is about $20 and about the same price as an OFL, so I don't see much advantage except possible extended engine live if every thing is done right. And one of my car's a diesel and the oil becomes black upon startup. So a color test won't do.

 

similar to Rotella and Cen-pe-co from a base standpoint. They manufacture oils for both gas and diesel engines, with ULX's reputation coming from diesel owners (mostly semis) who report 40k to 50k drain intervals without any adverse affects.....

From what I've seen, synthetics are typically 3X more expensive and not 5X as you've stated. Mobile 1 and Amsoil are $4 to $5/quart, while decent name-brand dino oil (such as Pennzoil) are more like $1.50 to $2/quart. Sure, you can buy that generic $.89/quart stuff, but I don't consider that valid for this comparison.

The primary reason behind choosing a synthetic is the longer drain interval, while its extended temperature range compared to dino oil would be more of a secondary reason.

Since you're good about changing your oil at shorter intervals, there's no real reason to stop what you're doing with your oil changes. You've got the right idea. But use gas oils for gas engines and diesel oils for diesel engines. Since the additive packages are no doubt different because of what a gas vs. diesel motor generates when running, its best to stick with the oil designed for your particular engine.

If you want to extend the drain interval out of laziness (which is my reason) on your Maxima, then give ULX or Amsoil a shot....