How important is doing oil samples on a Diesel engine. I have never done them for a gas engine, are diesel that much more critical? I only use it for light towing and some daily driving, at least for now, trying to slow down on the wife's car. It has 33000 miles and is only 1 1/2 yrs old. Trying to decide if I should be doing samples, I did regularly on my 6.0 I had in the past.

 

I did on my 7.3 but haven't yet on my 17. I wouldn't say they are critical but they can give you advance warning of increased wear that could indicate another problem that you can head off before it turns into a major issue. Not sure I even want to see a sample report on a diesel that is still breaking in, lol. I will probably start around 50000 miles and get a good base line before power train warranty runs out.

 

It's by no means imperative that you have a sample of used oil analyzed. Paying attention to the factory recommendations and using the correct oil is the most important thing along with the proper maintenace you can do. On the other-hand if you're using your truck under extreme conditions then it wouldn't hurt to have the engine oil analyzed at least once.

 

I did them all the time on my 6.0 - which had a propensity to sheer the oil (lowering its viscosity) - ford called for 7500 mile change intervals and a 15w40 oil would be sheered down to a 10w30 or less before you could reach 7000 miles (Including synthetics)

sampling showed I could safely run the oil to 6000 miles but I played it safe (and easy math) and changed at 5000 miles.

sampling will show you MORE than just premature engine/metal wear - it will alert you if you have coolant in the oil or fuel leaking (past the rings etc) into the oil - all will damage rod bearings quickly - among other things.

 

Unless, you suspect there is an issue I dont see the need. I did them on my 6.0 and used them in my 42+ pages of evidence for buyback/lemon law.

 

In different times oil sampling was a winner for fleets for they could save mega bucks and prevent catastrophic failure in advance, thus saving $$$$. The military did it and so did everyone else. The 2 culprits were engine assembly and the ultra high compression of diesels.

Before the advent of computer driven machining tolerances were very lose compared to today. Engine blocks were full of sand and metal shavings. Common was first oil change at 500 mi, then 1000mi, 3000mi and if your car burned regular gas change at 5000 mi, if high octane change at 3000 mi...all of this due to blow-by of gases generated in the combustion chamber blowing past the rings. In diesels it was worse due to the higher compression over gas engines.

In those days the fumes from cars and diesels would make you sick just driving behind them. Brand new cars would often consume oil at the rate of 1 qt to 500 miles.

Today's engines have better tolerances than the "blueprinted" engines that emerged in the 60's when I was racing. There is far less tailings left over inside the block, engines are cleaner and run cleaner.

As suggested in post #2, #3 no need to sample at less than 50k and FOLLOW the recommendations...

 

Thanks I'll save my money then. And just drive it, by the time I have 50k on it, with my past history, it will be well out of warranty any ways, I had a 2009 f150 traded for F250, it only had 30000 on it. My 2008 class A I traded on our Travel trailer 9nly had 2500, and of those 1200 was the delivery miles from the manufacturer.

 

It's worth doing occasionally to get a base line and monitor for changes. Years ago, Blackstone detected elevated potassium in a 2005 Duramax I owned and suggested it could be from a leaking EGR cooler. Sure enough, it had just barely started leaking even though there were no other symptoms or noticeable coolant loss yet.

At the very least, I would do one now and then again as you approach the end of the warranty period to catch any problems which haven't exhibited other symptoms.