Oil Change Mistake 30w instead of 40w

[h20diver]

Hi Everyone.
I have made an oil change mistake. I have a 1976 53 MY with 8V71TI with M20s with around 2600hrs and I live in southwest Florida. I used Rotella 30w in both mains and transmissions. I now realize that I should have used 40W in both. How much damage does anyone think this may cause in the coarse of six months ? I rarely run her on plane with an average of 1650 rpm. I will if needed drain both mains and transmissions to avoid any problems. Any help and or advice would be appreciated. Thanks... dumb mistake on my part.

 

[saltshaker]

You should be fine 30WT is recommended for use in colder climates. I ran 30WT in my M20's. They would shift better when cold.

 

[SKYCHENEY]

I agree with Jack. You should be fine. In future, however, I would recommend an oil other than the Rotella. There are much better oils out there for our old Detroits.

 

[tomrealest]

What are the current oil favorites for the 8v71TIs?

 

[SKYCHENEY]

Exxon XD3, Castrol Assurron,

 

[Canuck Dennis]

Anyone know what the micron rating is for the standard DD or Napa OIL filters ??

 

[Fanfare]

For 8V-71n DDs built in late 1965 the required oil for engines and for the Allison transmission was straight 30 weight, low ash oil. The only problem was that at the end of a long hard run, when going into neutral, the low oil pressure alarm would sound. At that time DD warned not to use 40 wt. A few years later, with no explanation that I was aware of, DD chamged to recommending straight 40 wt. Go figure.

I have heard that some users have gone to multi weight oils with no reported bad results. I would only do this in an emergency. Same for synthetic oils.

The Admiral's new Toyota Sienna says to use synthetic 0w-5 weight oil only, which was a surprise to me. Since we got 180,000 miles out of her 2003 model and we never added a quart of oil (other than annal changes of its synthetic oil) I plan on doing what the manual says.

 

[Genesis]

The reason for the change to 40wt was abnormal wear patterns on the camshafts with 30 that resulted in early overhauls. And changing a cam on these engines, especially when they're in a boat and are typically hard or close to hard-up against the forward ER bulkhead, is a major problem.

30 remained approved for under-freezing operation because 40, without an oil heater, simply was too thick to flow and you couldn't get enough RPMs for the engine to start in sub-freezing weather. The risk of abnormal cam wear was thus deemed acceptable .vs. "no-starts" for operation under those conditions. It is rather unlikely you'll be boating in sub-freezing conditions for obvious reasons. Attempts were made with multi-grade as well (e.g. 15w40) with the same results -- abnormal cam wear -- and the recommendation was retracted.

The problem is not with the valve cam lobes but rather with the cam lobe for the injectors, which are subject to higher loads. The same issue has come up with unit-injector engines from other manufacturers and oil specs are very important with those motors as well (e.g. VW's unit injector motors) for the same reason.

The risk of running 30 for one change interval is not particularly high, but I would not continue to use it. Abnormal camshaft wear is not something you want to have to deal with (aside from the cost of the parts and labor) as in nearly all boat installations it will require removal of the engine in order to gain sufficient access to replace it.

 

[h20diver]

Thanks for all the advice. I will change this 30w out in a few months to 40w. Caulk it up as another learning experience . I appreciate all the replies. Thanks